1,一条SMS最大字符数
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androidframeworksopt elephony中
com.android.internal.telephony.gsm.SmsMessage
编码——>ENCODING_7BIT
/** The maximum number of payload septets per message */
public static final int MAX_USER_DATA_SEPTETS = 160; //单条信息160个字节(ASCII码对应的纯英文字符)
/**
* The maximum number of payload septets per message if a user data header
* is present. This assumes the header only contains the
* CONCATENATED_8_BIT_REFERENCE element.
*/
public static final int MAX_USER_DATA_SEPTETS_WITH_HEADER = 153;//对于ASCII码对应的纯英文字符,长短信中每条短信的长度为153字节,7字节标记分页信息等协议
对于纯英文,1字符占用1字节
所以相当于第一条160个字符
第二条160-7-7=146个字符(第一条信息的协议信息也占用了第二条的长度)
第三条及以上,160-7=153个字符。
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编码——>ENCODING_16BIT (处理包含中文等非ASSICC码字符的短信)
/** The maximum number of payload bytes per message */
public static final int MAX_USER_DATA_BYTES = 140;//单条信息140个字节(包含中文等非ASCII码字符的信息)
/**
* The maximum number of payload bytes per message if a user data header
* is present. This assumes the header only contains the
* CONCATENATED_8_BIT_REFERENCE element.
*/
public static final int MAX_USER_DATA_BYTES_WITH_HEADER = 134;//包含中文等非ASCII码字符的信息,长短信每条最大长度为140-6=134字节,6个字节用于标记分页信息
对于包含中文字符的信息,1字符占用2字节,140/2=70, 134/2=67, 6/2=3
所以相当于第一条70个字符
第二条70-3-3=64字符(第一条信息的分页信息也占用了第二条的长度)
第三条及以上70-3=67字符。
参考文档:
长短信组织结构。UDH(user data header)
http://wenku.baidu.com/link?url=ksdB3TkIqKdm7tASZWqmZ8BJcUDbTbVw5FDWButs8pDlEM0ZuiJ7z36Z6lQDqZBA9vI-_XE1UWBvkRzQdeCY6wfK8labQsqIkZgQAZ7sZnK
2,SMS字符数达到多少会变成MMS
在MMS中可以配置达到多少条短信就转为彩信
ComposeMessageActivity中 updateCounter(.....)方法中有判断。
if (!MmsConfig.getMultipartSmsEnabled()) { // The provider doesn't support multi-part sms's so as soon as the user types // an sms longer than one segment, we have to turn the message into an mms. mWorkingMessage.setLengthRequiresMms(msgCount > 1, true); } else { int threshold = MmsConfig.getSmsToMmsTextThreshold(ComposeMessageActivity.this); //------ 这里定义了sms数量上限 mWorkingMessage.setLengthRequiresMms(threshold > 0 && msgCount > threshold, true); }
MmsConfig中
public static int getSmsToMmsTextThreshold(Context context) { int limitCount = context.getResources().getInteger(R.integer.limit_count); //先通过limit_count判断 if (limitCount != 0) { return limitCount; } return mSmsToMmsTextThreshold; //如果limit_count=0,则用 mSmsToMmsTextThreshold判断
}
mSmsToMmsTextThreshold值定义
private static int mSmsToMmsTextThreshold = -1;
......
} else if ("smsToMmsTextThreshold".equalsIgnoreCase(value)) { int maxSmstomms = context.getResources().getInteger(R.integer.config_max_smstomms); mSmsToMmsTextThreshold = (maxSmstomms == 0) ? Integer.parseInt(text) : maxSmstomms; }
信息中对于可以输入字符的数量并没有限制,如果不停的输入字符,数量达到上百条信息的字符数,对于内存较低的手机会出现卡顿现象。
那么我们做一个基本的限制,如40条信息的字符数作为上限
mTextEditorWatcher中增加对输入字符的数量判断
public void afterTextChanged(Editable s) { //-----------------add by antoon if(FEATURE_MMS_MESSAGE_COUNT_LIMIT){ int[] params=SmsMessage.calculateLength(mTextEditor.getText(), false); int length = 0; if(params[3]==SmsMessage.ENCODING_7BIT){ length = EN_ENCODE_MAX_LENGTH; //modified by antoon }else if(params[3] == SmsMessage.ENCODING_16BIT) { //modified by antoon length = CH_ENCODE_MAX_LENGTH; } if(mTextEditor.getText().length() > length) { s = s.delete(length, s.length()); toast(R.string.textContentLimit); } } //----------------end }
private static final int EN_ENCODE_MAX_LENGTH = 3060*2; // add by antoon
private static final int CH_ENCODE_MAX_LENGTH = 1340*2; //add by antoon
private static final boolean FEATURE_MMS_MESSAGE_COUNT_LIMIT=true; //add by antoon