OKhttp提供的示例不完整

Question

我将此代码放入一个新项目：

https://raw.githubusercontent.com/square/okhttp/master/samples/guide/src/main/java/okhttp3/guide/GetExample.java

我已将此添加到清单中

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

我已经添加了要引入的gradle组件，否则它甚至不会编译，但这段代码完全没有任何作用。当我在一个空的应用程序中复制应用程序时，它会崩溃。

我试着把它变成一个"；基本动作"；例如，它至少不会崩溃，但代码不会发出http请求。

package com.example.hellokitty;
import android.os.Bundle;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import java.io.IOException;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class MainActivity extends AppCompatActivity {
OkHttpClient client = new OkHttpClient();
String run(String url) throws IOException {
Request request = new Request.Builder()
.url(url)
.build();
try (Response response = client.newCall(request).execute()) {
return response.body().string();
}
}
public static void main(String[] args) throws IOException {
MainActivity example = new MainActivity();
String response = example.run("http://10.10.0.11/kek");
System.out.println(response);
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}

Answer 1

我试过你的代码。它崩溃是因为您在主线程上运行网络操作。你会得到NetworkOnMainThreadException运行时异常。

为了避免这种情况，您需要更换

try (Response response = client.newCall(request).execute()) {
return response.body().string();
}

带有

client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(@NotNull Call call, @NotNull IOException e) {
e.printStackTrace();
}
@Override
public void onResponse(@NotNull Call call, @NotNull Response response) throws IOException {
String url = response.body().string();
//your code here
}
});

整个代码将是：

public class MainActivity extends AppCompatActivity {
private OkHttpClient client;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
client = new OkHttpClient();

run("http://10.10.0.11/kek");
}
private void run(String url) {
Request request = new Request.Builder()
.url(url)
.build();
client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(@NotNull Call call, @NotNull IOException e) {
e.printStackTrace();
}
@Override
public void onResponse(@NotNull Call call, @NotNull Response response){
String url = response.body().toString();
//your code here
}
});
}
}

从Android 9(API 28级(开始，默认情况下会禁用明文支持。

所以当你打电话给http://10.10.0.11/kek您将收到java.io.IOException:不允许向*发送明文HTTP流量

这就是为什么您需要在安全配置中启用明文流量。

在你的AndroidManifest.xml中：

<?xml version="1.0" encoding="utf-8"?>
<manifest ...>
<uses-permission android:name="android.permission.INTERNET" />
<application
...
android:networkSecurityConfig="@xml/network_security_config"
...>
...
</application>
</manifest>

创建文件res/xml/network_security_config.xml：

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
<base-config cleartextTrafficPermitted="true"/>
</network-security-config>