Java调用Http/Https接口(2)--HttpURLConnection/HttpsURLConnection调用Http/Https接口

HttpURLConnection是JDK自身提供的网络类，不需要引入额外的jar包。文中所使用到的软件版本：Java 1.8.0_191。

1、服务端

参见Java调用Http接口(1)--编写服务端 

2、调用Http接口

2.1、GET请求

    public static void get() {
        try {
            String requestPath = "http://localhost:8080/demo/httptest/getUser?userId=1000&userName=" + URLEncoder.encode("李白", "utf-8");
            URL url = new URL(requestPath);
            //设置代理
            //InetSocketAddress addr = new InetSocketAddress("127.0.0.1", 8888);  
            //Proxy proxy = new Proxy(Proxy.Type.HTTP, addr);
            //connection = (HttpURLConnection)url.openConnection(proxy);
            
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("GET");
            connection.connect();
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("GET返回结果：" + back);
            } else {
                System.out.println("GET请求状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

2.2、POST请求(发送键值对数据）

    public static void post() {
        try {
            String requestPath = "http://localhost:8080/demo/httptest/getUser";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.connect();
            
            String param = "userId=1000&userName=李白";
            bytesToOutputStream(param.getBytes(), connection.getOutputStream());
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("POST返回结果：" + back);
            } else {
                System.out.println("POST返回状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

2.3、POST请求(发送JSON数据）

    public static void post2() {
        try {
            String requestPath = "http://localhost:8080/demo/httptest/addUser";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setRequestProperty("Content-type", "application/json");
            connection.connect();
            
            String param = "{"userId": "1001","userName":"杜甫"}";
            bytesToOutputStream(param.getBytes(), connection.getOutputStream());
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("POST2返回结果：" + back);
            } else {
                System.out.println("POST2返回状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

2.4、上传文件

    public static void upload() {
        try {
            String requestPath = "http://localhost:8080/demo/httptest/upload";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setRequestProperty("Content-type", "file/*");
            connection.connect();
            
            FileInputStream fileInputStream = new FileInputStream("d:/a.jpg");
            inputStreamToOutputStream(fileInputStream, connection.getOutputStream());
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("upload返回结果：" + back);
            } else {
                System.out.println("upload返回状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

2.5、上传文件及发送键值对数据

2.5.1、分析数据结构

通过抓包工具分析页面表单上传文件的过程，可以看出传输数据的结构：

 

2.5.2、根据分析出的数据结构编写代码

    public static void multi() {
        String BOUNDARY = java.util.UUID.randomUUID().toString();
        String TWO_HYPHENS = "--";
        String LINE_END = "
";
        FileInputStream in = null;
        try {
            String requestPath = "http://localhost:8080/demo/httptest/multi";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setDoInput(true);
            connection.setRequestProperty("Content-type", "multipart/form-data; BOUNDARY=" + BOUNDARY);
            connection.connect();
            
            StringBuffer sb = new StringBuffer();
            //封装键值对数据1
            sb.append(TWO_HYPHENS).append(BOUNDARY).append(LINE_END);
            sb.append("Content-Disposition: form-data; name="param1"").append(LINE_END);
            sb.append(LINE_END);
            sb.append("参数1").append(LINE_END);
            
            //封装键值对数据2
            sb.append(TWO_HYPHENS).append(BOUNDARY).append(LINE_END);
            sb.append("Content-Disposition: form-data; name="param2"").append(LINE_END);
            sb.append(LINE_END);
            sb.append("参数2").append(LINE_END);
            
            //封装文件数据
            sb.append(TWO_HYPHENS).append(BOUNDARY).append(LINE_END);
            sb.append("Content-Disposition: form-data; name="file"; filename="a.jpg"").append(LINE_END);
            sb.append("Content-Type: file/*").append(LINE_END);
            sb.append(LINE_END);

            bytesToOutputStream(sb.toString().getBytes(), connection.getOutputStream());

            in = new FileInputStream("d:/a.jpg");
            inputStreamToOutputStream(in, connection.getOutputStream());
            
            //写入标记结束位
            String end = (LINE_END + TWO_HYPHENS + BOUNDARY + TWO_HYPHENS + LINE_END);
            bytesToOutputStream(end.getBytes(), connection.getOutputStream());
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("multi返回结果：" + back);
            } else {
                System.out.println("multi返回状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            FileUtil.close(in);
        }
    }

2.5.3、上传文件方法变通

这种方式上传文件完全是模拟页面的提交行为来编码的，比较繁琐。可以把文件转成字符串，然后通过键值对传给服务端，服务端执行相反的过程来存储文件：

客户端：文件-> 字节数组->Base64字符串

服务端：Base64字符串-> 字节数组->文件

按照这种方式来实现应该比较容易，这里就不演示了。

2.6、下载文件

    public static void download() {
        FileOutputStream out = null;
        try {
            String requestPath = "http://localhost:8080/demo/httptest/download";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.connect();
            System.out.println("download返回状态码：" + connection.getResponseCode());
            String contentDisposition = connection.getHeaderField("Content-Disposition");//attachment; filename="a.jpg"
            String fileName = "none";
            if (contentDisposition != null && contentDisposition.indexOf("filename") > -1) {
                fileName = contentDisposition.substring(contentDisposition.indexOf(""") + 1, contentDisposition.length() - 1);
                fileName = java.net.URLDecoder.decode(fileName, "utf-8");
            }
            out = new FileOutputStream("d:/temp/dowload_" + System.currentTimeMillis() + "_" + fileName);
            inputStreamToOutputStream(connection.getInputStream(), out);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            FileUtil.close(out);
        }
    }

2.7、完整例子

package com.inspur.demo.http.client;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
//import java.net.InetSocketAddress;
//import java.net.Proxy;
import java.net.URL;
import java.net.URLEncoder;

import com.inspur.demo.common.util.FileUtil;

/**
 * 
 * 通过HttpURLConnection调用Http接口
 *
 */
public class HttpURLConnectionCase {
    /**
     * GET请求
     */
    public static void get() {
        try {
            String requestPath = "http://localhost:8080/demo/httptest/getUser?userId=1000&userName=" + URLEncoder.encode("李白", "utf-8");
            URL url = new URL(requestPath);
            //设置代理
            //InetSocketAddress addr = new InetSocketAddress("127.0.0.1", 8888);  
            //Proxy proxy = new Proxy(Proxy.Type.HTTP, addr);
            //connection = (HttpURLConnection)url.openConnection(proxy);
            
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("GET");
            connection.connect();
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("GET返回结果：" + back);
            } else {
                System.out.println("GET请求状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    /**
     * POST请求，发送键值对数据
     */
    public static void post() {
        try {
            String requestPath = "http://localhost:8080/demo/httptest/getUser";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.connect();
            
            String param = "userId=1000&userName=李白";
            bytesToOutputStream(param.getBytes(), connection.getOutputStream());
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("POST返回结果：" + back);
            } else {
                System.out.println("POST返回状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    /**
     * POST请求，发送json格式数据
     */
    public static void post2() {
        try {
            String requestPath = "http://localhost:8080/demo/httptest/addUser";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setRequestProperty("Content-type", "application/json");
            connection.connect();
            
            String param = "{"userId": "1001","userName":"杜甫"}";
            bytesToOutputStream(param.getBytes(), connection.getOutputStream());
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("POST2返回结果：" + back);
            } else {
                System.out.println("POST2返回状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    /**
     * 上传文件
     */
    public static void upload() {
        try {
            String requestPath = "http://localhost:8080/demo/httptest/upload";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setRequestProperty("Content-type", "file/*");
            connection.connect();
            
            FileInputStream fileInputStream = new FileInputStream("d:/a.jpg");
            inputStreamToOutputStream(fileInputStream, connection.getOutputStream());
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("upload返回结果：" + back);
            } else {
                System.out.println("upload返回状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    /**
     * 上传文件及发送键值对数据
     */
    public static void multi() {
        String BOUNDARY = java.util.UUID.randomUUID().toString();
        String TWO_HYPHENS = "--";
        String LINE_END = "
";
        FileInputStream in = null;
        try {
            String requestPath = "http://localhost:8080/demo/httptest/multi";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setDoInput(true);
            connection.setRequestProperty("Content-type", "multipart/form-data; BOUNDARY=" + BOUNDARY);
            connection.connect();
            
            StringBuffer sb = new StringBuffer();
            //封装键值对数据1
            sb.append(TWO_HYPHENS).append(BOUNDARY).append(LINE_END);
            sb.append("Content-Disposition: form-data; name="param1"").append(LINE_END);
            sb.append(LINE_END);
            sb.append("参数1").append(LINE_END);
            
            //封装键值对数据2
            sb.append(TWO_HYPHENS).append(BOUNDARY).append(LINE_END);
            sb.append("Content-Disposition: form-data; name="param2"").append(LINE_END);
            sb.append(LINE_END);
            sb.append("参数2").append(LINE_END);
            
            //封装文件数据
            sb.append(TWO_HYPHENS).append(BOUNDARY).append(LINE_END);
            sb.append("Content-Disposition: form-data; name="file"; filename="a.jpg"").append(LINE_END);
            sb.append("Content-Type: file/*").append(LINE_END);
            sb.append(LINE_END);

            bytesToOutputStream(sb.toString().getBytes(), connection.getOutputStream());

            in = new FileInputStream("d:/a.jpg");
            inputStreamToOutputStream(in, connection.getOutputStream());
            
            //写入标记结束位
            String end = (LINE_END + TWO_HYPHENS + BOUNDARY + TWO_HYPHENS + LINE_END);
            bytesToOutputStream(end.getBytes(), connection.getOutputStream());
            
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                byte[] b = getBytesFromInputStream(connection.getInputStream());
                String back = new String(b);
                System.out.println("multi返回结果：" + back);
            } else {
                System.out.println("multi返回状态码：" + connection.getResponseCode());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            FileUtil.close(in);
        }
    }
    
    /**
     * 下载文件
     */
    public static void download() {
        FileOutputStream out = null;
        try {
            String requestPath = "http://localhost:8080/demo/httptest/download";
            URL url = new URL(requestPath);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setRequestMethod("POST");
            connection.connect();
            System.out.println("download返回状态码：" + connection.getResponseCode());
            String contentDisposition = connection.getHeaderField("Content-Disposition");//attachment; filename="a.jpg"
            String fileName = "none";
            if (contentDisposition != null && contentDisposition.indexOf("filename") > -1) {
                fileName = contentDisposition.substring(contentDisposition.indexOf(""") + 1, contentDisposition.length() - 1);
                fileName = java.net.URLDecoder.decode(fileName, "utf-8");
            }
            out = new FileOutputStream("d:/temp/dowload_" + System.currentTimeMillis() + "_" + fileName);
            inputStreamToOutputStream(connection.getInputStream(), out);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            FileUtil.close(out);
        }
    }
    
    /**
     * 从输入流获取数据
     * @param in
     * @return
     * @throws IOException
     */
    private static byte[] getBytesFromInputStream(InputStream in) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        byte[] b = new byte[1024];
        int len;
        while ((len = in.read(b)) != -1) {
            out.write(b, 0, len);
        }
        byte[] bytes = out.toByteArray();
        out.close();
        return bytes;
    }
    
    /**
     * 把字节数组写入输出流
     * @param bytes
     * @param out
     * @throws IOException
     */
    private static void bytesToOutputStream(byte[] bytes, OutputStream out) throws IOException {
        ByteArrayInputStream in = new ByteArrayInputStream(bytes);
        byte[] b = new byte[1024];
        int len;
        while ((len = in.read(b)) != -1) {
            out.write(b, 0, len);
        }
        out.flush();
        in.close();
    }
    
    /**
     * 从输入流读取数据并写入输出流
     * @param out
     * @param bytes
     * @throws IOException
     */
    private static void inputStreamToOutputStream(InputStream in, OutputStream out) throws IOException {
        byte[] b = new byte[1024];
        int len;
        while ((len = in.read(b)) != -1) {
            out.write(b, 0, len);
        }
        out.flush();
    }
    
    public static void main(String[] args) {
        get();
        post();
        post2();
        upload();
        multi();
        download();
    }
}

3、调用Https接口

调用Https接口需要用HttpsURLConnection，与调用Http接口不一样的部分主要在设置ssl部分，下面用GET请求来演示ssl的设置，其他调用方式类似。

3.1、导入cer证书

对于自定义证书的网站，需把证书用java自带的工具keytool导入本地，如导入到d:/temp目录下

cd d:/temp
keytool -import -alias aa -keystore cacerts -file aa.cer -trustcacerts

如果当前目录已有cacerts证书库，则需输入密码；如果没有则需设置密码，会在当前目录下生成cacerts证书库。

也可以不导入，使用默认实现的DefaultTrustManager，信任所有，将导致不安全。

3.2、示例

package com.inspur.demo.http.client;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.security.KeyStore;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.KeyManager;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

import com.inspur.demo.common.util.FileUtil;


/**
 * 通过HttpsURLConnection调用Https接口
 */
public class HttpsURLConnectionCase {
    public static void main(String[] args) {
        try {
            /*
             * 请求有权威证书的地址
             */
            String requestPath = "https://www.baidu.com/";
            HttpsURLConnection connection = getHttpsURLConnection(requestPath, "GET");
            String result = new String(getBytesFromInputStream(connection.getInputStream()));
            System.out.println("GET1返回结果：" + result);
            
            /*
             * 请求自定义证书的地址
             */
            //获取信任库
            KeyStore trustStore = getkeyStore("jks", "d:/temp/cacerts", "123456");
            
            //不需客户端证书
            requestPath = "https://x.x.x.x:9010/zsywservice";
            connection = getHttpsURLConnection(requestPath, "GET", null, null, trustStore);
            result = new String(getBytesFromInputStream(connection.getInputStream()));
            System.out.println("GET2返回结果：" + result);
          
            //需客户端证书
            requestPath = "https://x.x.x.x:9016/zsywservice";
            KeyStore keyStore = getkeyStore("pkcs12", "d:/client.p12", "123456");
            connection = getHttpsURLConnection(requestPath, "GET", keyStore, "123456", trustStore);
            result = new String(getBytesFromInputStream(connection.getInputStream()));
            System.out.println("GET3返回结果：" + result);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    

    /**
     * 获取证书
     * @return
     */
    private static KeyStore getkeyStore(String type, String filePath, String password) {
        KeyStore keySotre = null;
        FileInputStream in = null;
        try {
            keySotre = KeyStore.getInstance(type);
            in = new FileInputStream(new File(filePath));
            keySotre.load(in, password.toCharArray());
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            FileUtil.close(in);
        }
        return keySotre;
    }

    private static HttpsURLConnection getHttpsURLConnection(String uri, String method) throws Exception {
        URL url = new URL(uri);
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
        connection.setRequestMethod(method);
        connection.setDoInput(true);
        connection.setDoOutput(true);
        return connection;
    }
    
    /**
     * 获取连接
     * @param uri
     * @param method
     * @param keyStore
     * @param trustStore
     * @return
     * @throws Exception
     */
    private static HttpsURLConnection getHttpsURLConnection(String uri, String method, KeyStore keyStore, String keyStorePassword, KeyStore trustStore) throws Exception {
        KeyManager[] keyManagers = null;
        TrustManager[] trustManagers = null;
        if (keyStore != null) {
            KeyManagerFactory keyManagerFactory = KeyManagerFactory.getInstance("SunX509");
            keyManagerFactory.init(keyStore, keyStorePassword.toCharArray());
            keyManagers = keyManagerFactory.getKeyManagers();
        }
        if (trustStore != null) {
            TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance("SunX509");
            trustManagerFactory.init(trustStore);
            trustManagers = trustManagerFactory.getTrustManagers();
        } else {
            trustManagers = new TrustManager[] { new DefaultTrustManager()};
        }
        
        //设置服务端支持的协议
        SSLContext context = SSLContext.getInstance("TLSv1.2");
        context.init(keyManagers, trustManagers, null);
        SSLSocketFactory sslFactory = context.getSocketFactory();

        URL url = new URL(uri);
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
        connection.setSSLSocketFactory(sslFactory);
        //验证URL的主机名和服务器的标识主机名是否匹配
        connection.setHostnameVerifier(new HostnameVerifier() {
            @Override
            public boolean verify(String hostname, SSLSession session) {
                //if ("xxx".equals(hostname)) {
                //    return true;
                //} else {
                //    return false;
                //}
                return true;
            }
        });
        connection.setRequestMethod(method);
        connection.setDoInput(true);
        connection.setDoOutput(true);
        return connection;
    }
    
    /**
     * 默认的TrustManager实现，不安全
     */
    private static final class DefaultTrustManager implements X509TrustManager {
        @Override
        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
        }

        @Override
        public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
        }

        @Override
        public X509Certificate[] getAcceptedIssuers() {
            return null;
        }
    }
    
    /**
     * 从输入流获取数据
     * @param in
     * @return
     * @throws IOException
     */
    private static byte[] getBytesFromInputStream(InputStream in) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        byte[] b = new byte[1024];
        int len;
        while ((len = in.read(b)) != -1) {
            out.write(b, 0, len);
        }
        byte[] bytes = out.toByteArray();
        out.close();
        return bytes;
    }
}

3.2、Received fatal alert:handshake_failure

 出现这种这种问题的一种情况是由于客户端使用的协议，服务端不支持造成的；修改为服务端所支持的协议即可。在getHttpsURLConnection方法中修改：

SSLContext context = SSLContext.getInstance("TLSv1.2");

可选的协议参数有：SSL、SSLv2、SSLv3、TLS、TLSv1、TLSv1.1、TLSv1.2；TLS是SSL标准化的产物，故现在基本只使用TLS相关的参数。

可以用linux的curl命令来测试服务端支持哪些协议：

curl -k https://x.x.x.x:9016/zsywservice --tlsv1.2 -v

可选协议有：--tlsv1、--tlsv1.0、--tlsv1.1、--tlsv1.2、--tlsv1.3

如果出现如下信息，则表示不支持：