Android Java 必备：Socket通信

Android Java 必备：Socket通信

目标

Demo是通过Java ServerSocket 和 Socket 通信实现客户端发送消息和发送文件到服务器,服务器接收到消息和文件，并且实现解决inputStream.read()的阻塞问题思路。

服务器端

创建ServerSocket服务器

serverSocket = new ServerSocket(port);//首先创建一个服务端口

//等待客户端的连接请求

socket = serverSocket.accept();

等待Socket客户端连接

//等待客户端的连接请求

socket = serverSocket.accept();

final String socketAddress =

socket.getRemoteSocketAddress().toString();

runOnUiThread(new Runnable() {

@Override

public void run() {

Toast.makeText(ServerActivity.this, \"成功建立与客户端的连接 : \" + socketAddress, Toast.LENGTH_SHORT).show();

Log.i(\"Lin\成功建立与客户端的连接 : \" + socketAddress);

}

});

接收Socket客户端信息

为了防止接收消息时，服务器inputStream.read()读取消息时产生阻塞，以换行符**(\"\\n\")结束inputStream.read()**

byte[] bytes = new byte[1];

StringBuilder info = new StringBuilder();

while (inputStream.read(bytes) != -1) {

String str = new String(bytes);

if (str.equals(\"\\n\")) {

break;

}

info.append(new String(bytes));

}

final String finalInfo = info.toString();

Log.i(\"Lin\

runOnUiThread(new Runnable() {

@Override

public void run() {

mEtReceive.setText(mEtReceive.getText().toString() + socketAddress + \" : \" +

finalInfo + \"\\n\");

}

});

接收Socket客户端文件

为了防止接收消息时，服务器inputStream.read()接受文件时产生阻塞，以文件MD5校验码进行校验，从而结束inputStream.read()

byte[] remote = new byte[32];

String md5 = \"\";

if (inputStream.read(remote) != -1) {

md5 = nullOfString(new String(remote));

}

final String root = Environment.getExternalStorageDirectory().getPath();

Log.i(\"Lin\

byte[] inputByte = new byte[1024 * 1024];

int len = 0;

long fileSize = 0;

DataInputStream dis = new DataInputStream(inputStream);

// 文件名和长度

String fileName = dis.readUTF();

final long fileLength = dis.readLong();

Log.i(\"Lin\

Log.i(\"Lin\

mPath = root + \"/ECG/\" + fileName;

File file = new File(root + \"/ECG/\");

if (!file.exists()) file.mkdir();

file = new File(mPath);

FileOutputStream fileOutputStream = new FileOutputStream(file);

String fileMD5 = nullOfString(getFileMD5(new File(mPath)));

while (!md5.equals(fileMD5) && (len = dis.read(inputByte, 0, inputByte.length)) > 0) {

fileSize += len;

fileOutputStream.write(inputByte, 0, len);

fileOutputStream.flush();

fileMD5 = nullOfString(getFileMD5(new File(mPath)));

Log.i(\"Lin\fileMD5);

Log.i(\"Lin\fileSize = \" + fileSize + \" \" + (fileSize * 100 / fileLength) + \"%\")

;

final long finalFileSize = fileSize;

runOnUiThread(new Runnable() {

@Override

public void run() {

mProgressDialog.setMessage((finalFileSize * 100 / fileLength) + \"%\");

mProgressDialog.show();

}

});

if (md5.equals(fileMD5)) {

fileOutputStream.close();

runOnUiThread(new Runnable() {

@Override

public void run() {

mProgressDialog.hide();

}

});

getFileMD5(file));

File(mPath)));

}

}

Log.i(\"Lin\fileMD5 = nullOfString(getFileMD5(new Log.i(\"Lin\

final String finalFileMD = fileMD5;

final String finalMd = md5;

runOnUiThread(new Runnable() {

@Override

public void run() {

mEtReceive.setText(mEtReceive.getText().toString() + \"文件路径：\" + mPath + \"\\n\");

mEtReceive.setText(mEtReceive.getText().toString() + \"file = \" + finalFileMD + \"\\n\");

mEtReceive.setText(mEtReceive.getText().toString() + \"text = \" + finalMd + \"\\n\");

}

});

客户端

创建Socket客户端

连接ServerSocket服务器

socket = new Socket();

socket.connect(new InetSocketAddress(ip, port));

//ip= 服务器ip

//port= 服务器端口

向ServerSocket服务器发送消息

try {

if (socket == null) return;

OutputStream om = socket.getOutputStream();

om.write(Constant.SERVER_TEXT.getBytes());

om.write(returnServer.getBytes());

om.write(\"\\n\".getBytes());//[10]

om.flush();

} catch (Exception e) {

e.printStackTrace();

Log.i(\"Lin\

}

为了防止发送消息时，服务器inputStream.read()读取消息时产生阻塞，客户端以换行符结束发送(om.write(\"\\n\".getBytes());)

向ServerSocket服务器发送文件

File file = new File(finalImagePath);

if (file.exists()) {

final String fileMD5 = nullOfString(getFileMD5(file));

OutputStream outputStream = socket.getOutputStream();

runOnUiThread(new Runnable() {

@Override

public void run() {

mEtReceive.setText(mEtReceive.getText().toString() + \"file = \" + fileMD5 + \"\\n\");

}

});

FileInputStream fileInputStream = new FileInputStream(file);

outputStream.write(Constant.SERVER_FILE.getBytes());

outputStream.flush();

outputStream.write(fileMD5.getBytes());

outputStream.flush();

DataOutputStream dis = new DataOutputStream(outputStream);

// 文件名和长度

dis.writeUTF(file.getName());

dis.flush();

dis.writeLong(file.length());

dis.flush();

byte[] buffer = new byte[1024 * 1024];

int len = 0;

while ((len = fileInputStream.read(buffer, 0, buffer.length)) > 0) {

dis.write(buffer, 0, len);

dis.flush();

}

fileInputStream.close();

Log.i(\"Lin\传输成功\");

}

为了防止发送文件时，服务器inputStream.read()接受文件时产生阻塞，客户端先向服务器发送文件MD5校验码再发送文件，服务器对接收文件进行校验从而结束**inputStream.read()**阻塞。

Demo中发送格式

字符：SERVER_TEXT + 字符 + 换行符（\\n）

文件：SERVER_FILE + 文件MD5校验码 + 文件

获取文件MD5

private static String getFileMD5(File file) {

if (!file.isFile()) {

return null;

}

MessageDigest digest;

FileInputStream in;

try {

byte[] buffer = new byte[1024];

int len;

digest = MessageDigest.getInstance(\"MD5\");

in = new FileInputStream(file);

while ((len = in.read(buffer, 0, 1024)) != -1) {

digest.update(buffer, 0, len);

}

in.close();

BigInteger bigInt = new BigInteger(1, digest.digest());

return bigInt.toString(16);

} catch (Exception e) {

e.printStackTrace();

return null;

}

}

THE END