Android原生目前支持两种方式访问http协议的网络，第一种是HttpURLConnection,另外一种是oKHttp,下面来介绍一下用HttpURLConnection来访问访问http协议的方法
第一步：添加网络访问权限
在AndroidManifest.xml文件中添加如下权限
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
http请求需要在 AndroidManifest.xml文件的application节点添加如下属性
android:usesCleartextTraffic="true"
第二步：使用HttpURLConnection访问网络
首先我们需要得到HttpURLConnection的实例，获取HttpURLConnection的方法如下
URL url = new URL("http://baidu.com");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
拿到HttpURLConnection的实例以后我们可以通过HttpURLConnection的实例来设置一些http请求的方式
urlConnection.setRequestMethod("GET");
urlConnection.setConnectTimeout(8000);
urlConnection.setRequestProperty("key","value");
| 方法名 | 含义 |
|---|---|
| setRequestMethod | 请求方式（常见的包括GET和POST等） |
| setConnectTimeout | 请求超时时间 |
| setRequestProperty | 请求中带的参数 |
请求发送出去以后，我们就可以通过HttpURLConnection的实例拿到请求的返回数据
InputStream inputStream = urlConnection.getInputStream();// 字节流
Reader reader = new InputStreamReader(inputStream);//字符流
BufferedReader bufferedReader = new BufferedReader(reader);// 缓存流
然后我们就可以从缓存流bufferedReader中读取数据
StringBuilder result = new StringBuilder();;
String temp;
while ((temp = bufferedReader.readLine()) != null) {
result.append(temp);
}
Log.i("MainActivity", result.toString());
读完数据以后不要忘记把数据流关闭哦
if (reader!=null){
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (inputStream!=null){
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (bufferedReader!=null){
try {
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (urlConnection != null){
urlConnection.disconnect();
}
网络请求访问我们还需要放到子线程中去
new Thread(){
@Override
public void run() {
super.run();
getNetwork();
}
}.start();
把得到的数据切到主线程中用文本展示出来
runOnUiThread(new Runnable() {
@Override
public void run() {
mTextView.setText(result);
}
});
代码示例
完整代码如下
MainActivity.java
package com.lucashu.http;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.URL;
public class MainActivity extends AppCompatActivity {
TextView mTextView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = findViewById(R.id.button);
mTextView = findViewById(R.id.textView);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new Thread(){
@Override
public void run() {
super.run();
getNetwork();
}
}.start();
}
});
}
private void getNetwork() {
InputStream inputStream = null;
Reader reader = null;
BufferedReader bufferedReader = null;
HttpURLConnection urlConnection = null;
try {
URL url = new URL("http://baidu.com");
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setConnectTimeout(8000);
urlConnection.setRequestProperty("key","value");
inputStream = urlConnection.getInputStream();// 字节流
reader = new InputStreamReader(inputStream);//字符流
bufferedReader = new BufferedReader(reader);// 缓存流
final StringBuilder result = new StringBuilder();;
String temp;
while ((temp = bufferedReader.readLine()) != null) {
result.append(temp);
}
Log.i("MainActivity", result.toString());
runOnUiThread(new Runnable() {
@Override
public void run() {
mTextView.setText(result);
}
});
inputStream.close();
reader.close();
bufferedReader.close();
} catch (Exception e) {
Log.i("MainActivity", e.getMessage());
e.printStackTrace();
}finally {
if (reader!=null){
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (inputStream!=null){
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (bufferedReader!=null){
try {
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (urlConnection != null){
urlConnection.disconnect();
}
}
}
}
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.lucashu.http">
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme"
android:usesCleartextTraffic="true">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.323" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="96dp"
android:text="访问网络数据"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
