Android http通信 HttpURLConnection

post 请求：

package com.example.administrator.eschool;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private EditText username;
    private EditText password;
    private Button login;

    private Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            textView.setText(msg.obj.toString());
        }
    };
    private TextView textView;
    private String text = "";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {
        username = (EditText) findViewById(R.id.username);
        password = (EditText) findViewById(R.id.password);
        login = (Button) findViewById(R.id.login);

        login.setOnClickListener(this);
        textView = (TextView) findViewById(R.id.textView);
        textView.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.login:
                submit();
                break;
        }
    }

    private void submit() {
        // validate
        final String usernameString = username.getText().toString().trim();
        if (TextUtils.isEmpty(usernameString)) {
            Toast.makeText(this, "请输入您的用户名", Toast.LENGTH_SHORT).show();
            return;
        }

        final String passwordString = password.getText().toString().trim();
        if (TextUtils.isEmpty(passwordString)) {
            Toast.makeText(this, "请输入您的密码", Toast.LENGTH_SHORT).show();
            return;
        }

        // TODO validate success, do something

        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    HttpURLConnection conn = (HttpURLConnection) new URL("http://192.168.1.107:8000/iphone_api/login.html").openConnection();
                    conn.setRequestMethod("POST");
                    conn.setConnectTimeout(5000);
                    conn.setDoOutput(true);
                    conn.setDoInput(true);

                    StringBuffer params = new StringBuffer();
                    // 表单参数与get形式一样
                    params.append("uid").append("=").append(usernameString).append("&")
                            .append("pwd").append("=").append(passwordString);
                    byte[] bypes = params.toString().getBytes();
                    conn.getOutputStream().write(bypes);// 输入参数

                    int code = conn.getResponseCode();
                    if (code == 200) {
                        InputStream is = conn.getInputStream();
                        ByteArrayOutputStream baos = new ByteArrayOutputStream();
                        byte[] buffer = new byte[1024];
                        int len = 0;
                        while ((len = is.read(buffer)) != -1) {
                            baos.write(buffer, 0, len);
                        }
                        is.close();
                        text = new String(baos.toByteArray(), "utf-8");
                        Message m = new Message();
                        m.obj = text;
                        mHandler.sendMessage(m);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();

    }
}