This experiment is to investigate the HttpURLConnection and Handler mechanism, etc., and the html file of the URL is obtained through the input URL and displayed on the interface. The following is the rendering:
First xml code:
activity_main66.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">
<LinearLayout
android:id="@+id/linearLayout"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="5dp"
android:layout_marginTop="5dp"
android:layout_marginEnd="5dp"
android:layout_marginBottom="5dp"
android:orientation="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="9"
android:gravity="center"
android:orientation="horizontal">
<EditText
android:id="@+id/et_url"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="9"
android:ems="10"
android:layout_marginRight="5dp"
android:inputType="textPersonName"
android:hint="请输入网址"
android:text="" />
<Button
android:id="@+id/btn_search"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="查看" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:orientation="horizontal">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="@+id/txt_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="" />
</LinearLayout>
</ScrollView>
</LinearLayout>
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>Logical Java code:
MainActivity66
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
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.net.HttpURLConnection;
import java.net.URL;
public class MainActivity66 extends AppCompatActivity {
TextView txt_content;
EditText et_url;
Button btn_search;
final int REQUEST_CODE = 1;
Handler handler = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main66);
txt_content = findViewById(R.id.txt_content);
et_url = findViewById(R.id.et_url);
btn_search = findViewById(R.id.btn_search);
//动态权限处理
if (ContextCompat.checkSelfPermission(this, Manifest.permission.INTERNET)
!= PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.INTERNET}, REQUEST_CODE);
}
//Handler处理
handler = new Handler(new Handler.Callback() {
@Override
public boolean handleMessage(@NonNull Message message) {
String str = (String) message.obj;
txt_content.setText(str);
return true;
}
});
btn_search.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String urlStr = et_url.getText().toString().trim();
if(urlStr.equals("")){
Toast.makeText(MainActivity66.this, "请输入网址",Toast.LENGTH_LONG).show();
}else{
new Thread(){ //网络访问必须放在线程中进行，创建一个无名线程对象
@Override
public void run() {
URL url = null;
try {
url = new URL(urlStr);
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
InputStream is = conn.getInputStream();
byte a = (byte) is.read(); //先读取1个字节
byte[] buffer = new byte[is.available()]; //再定义剩余的字节数组
is.read(buffer); //读取剩余的字节到buffer中
//定义字节数组输出流类对象，目的是将开始的1个字节和后面的字节组合到一起
ByteArrayOutputStream out = new ByteArrayOutputStream();
out.write(a);
out.write(buffer);
String str = out.toString();
Message msg = new Message(); //定义消息对象
msg.obj = str;
handler.sendMessage(msg); //将消息发送到消息队伍中
conn.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
}.start(); //启动线程
}
}
});
}
//动态权限请求回调方法
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == REQUEST_CODE) {
if (grantResults.length != 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Toast.makeText(this, "权限开启成功", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(this, "权限开启失败", Toast.LENGTH_LONG).show();
}
}
}
}In addition, you also need to do some network configuration
Add a statement in the AndroidManifest.xml file: declare network permissions
<uses-permission android:name="android.permission.INTERNET" />In addition, the higher version of Android also needs to complete the network security access configuration
Create an xml folder under the res folder and create a new file network_config.xml
The content is:
<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
<base-config cleartextTrafficPermitted="true"/>
</network-security-config>And also need to return to AndroidManifest.xml, add a sentence
android:networkSecurityConfig="@xml/network_config"
