java HTP协议之HttpConnUtil

package com.catstudio.user.client.interstellar;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpConnUtil {

public static HttpURLConnection connect(String address) throws IOException {
URL url = new URL(address);
HttpURLConnection httpUrlConnection = (HttpURLConnection) url.openConnection();
httpUrlConnection.setRequestMethod("POST");
httpUrlConnection.setDoOutput(true);
httpUrlConnection.setDoInput(true);
httpUrlConnection.connect();
return httpUrlConnection;
}

public static void close(InputStream din) {
if (din != null) {
try {
din.close();
} catch (IOException e) {
e.printStackTrace();
}
din = null;
}
}

public static void close(OutputStream dou) {
if (dou != null) {
try {
dou.close();
} catch (IOException e) {
e.printStackTrace();
}
dou = null;
}
}

public static void close(HttpURLConnection conn) {
if (conn != null) {
conn.disconnect();
conn = null;
}
}

/**
* 获取DataInputStream，当in 数据中没有数据，或者数据长度小于4个字节（无效请求）的时候返回null
*
* @param conn
* @return
*/
public static DataInputStream getDataInputStream(InputStream in) {
if (in == null) {
return null;
}
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(baos);
// 读取数据到缓冲流
try {
while (true) {
int b = in.read();
if (b == -1) {
break;
}
dos.write(b);
}
} catch (IOException e) {
e.printStackTrace();
}

byte[] bytes = baos.toByteArray();
// 关闭暂时的流
HttpConnUtil.close(dos);
HttpConnUtil.close(baos);
// 无效数据长度
if (bytes.length < 4) {
return null;
}
// 返回新的流
return new DataInputStream(new ByteArrayInputStream(bytes));
}

/**
* 获取DataInputStream，当in 数据中没有数据，或者数据长度小于4个字节（无效请求）的时候返回null
*
* @param conn
* @return
*/
public static DataInputStream getGzipDataInputStream(InputStream in) {
if (in == null) {
return null;
}
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(baos);
// 读取数据到缓冲流
try {
while (true) {
int b = in.read();
if (b == -1) {
break;
}
dos.write(b);
}
} catch (IOException e) {
e.printStackTrace();
}

byte[] bytes = null;
try {
bytes = baos.toByteArray();
} catch (Exception e) {
e.printStackTrace();
}

// System.out.println("字节长度：" + bytes.length);
// 关闭暂时的流
byte[] gbipByte = GZipUtil.uncompress(bytes);
// System.out.println("解压后长度：" + gbipByte.length);
HttpConnUtil.close(dos);
HttpConnUtil.close(baos);
// 无效数据长度
if (bytes.length < 4) {
return null;
}
// 返回新的流
return new DataInputStream(new ByteArrayInputStream(gbipByte));
}

}

在getDataInputStream方法中，之所以会重新write一遍，是为了防止数据流被截断。第二个有趣的地方是：ByteArrayOutputStream baos = new ByteArrayOutputStream();

DataOutputStream dos = new DataOutputStream(baos); 这样写之后，操作dos就会操作baos，因为他俩操作的是同一个数据流，持有的是同一个引用。相当于c++中传递指针那样，最后还是会对同一个对象进行操作。