我有一个简单的类写在Android Studio:

package com.mysite.myapp;

import org.apache.http.client.HttpClient;

public class Whatever {
    public void headBangingAgainstTheWallExample () {
        HttpClient client = new DefaultHttpClient();
    }
}

从这里我得到了以下编译时错误:

无法解析HttpClient符号

HttpClient不是包含在Android Studio SDK中吗?即使不是,我也像这样把它添加到我的Gradle构建中:

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:23.0.0'
    compile 'org.apache.httpcomponents:httpclient:4.5'
}

不管有没有最后一个编译行,错误都是一样的。我错过了什么?


当前回答

适用于android API 28及更高版本 在Manifest.xml应用程序标签内

    <application
    .
    .
    .

    <uses-library android:name="org.apache.http.legacy" android:required="false"/>

其他回答

如果你需要sdk 23,把这个添加到你的gradle:

android {
    useLibrary 'org.apache.http.legacy'
}

在SDK级别23中使用Apache HTTP:

顶层构建。Gradle - /build.gradle

buildscript {
    ...
    dependencies {
        classpath 'com.android.tools.build:gradle:1.5.0' 
        // Lowest version for useLibrary is 1.3.0
        // Android Studio will notify you about the latest stable version
        // See all versions: http://jcenter.bintray.com/com/android/tools/build/gradle/
    }
    ...
}

Android工作室关于gradle更新的通知:

特定于模块的构建。Gradle - /app/build.gradle

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"
    ...
    useLibrary 'org.apache.http.legacy'
    ...
}

在sdk 23中不再支持HttpClient。你必须使用URLConnection或降级到sdk 22(编译'com.android.support:appcompat-v7:22.2.0')

如果你需要sdk 23,把这个添加到你的gradle:

android {
    useLibrary 'org.apache.http.legacy'
}

你也可以尝试下载并将HttpClient jar直接包含到你的项目中,或者使用OkHttp代替

如前所述,org.apache.http.client.HttpClient在以下版本中不再被支持:

SDK (API级别)#23。

你必须使用java。net。httpurlconnection。

如果你想让你的代码(和生活)在使用HttpURLConnection时更容易,这里是这个类的包装器,它可以让你使用JSON对GET、POST和PUT进行简单的操作,例如,执行HTTP PUT。

HttpRequest request = new HttpRequest(API_URL + PATH).addHeader("Content-Type", "application/json");
int httpCode = request.put(new JSONObject().toString());
if (HttpURLConnection.HTTP_OK == httpCode) {
    response = request.getJSONObjectResponse();
} else {
  // log error
}
httpRequest.close()

请随意使用。

package com.calculistik.repository;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

/**
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * <p>
 * Copyright © 2017, Calculistik . All rights reserved.
 * <p>
 * Oracle and Java are registered trademarks of Oracle and/or its
 * affiliates. Other names may be trademarks of their respective owners.
 * <p>
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common
 * Development and Distribution License("CDDL") (collectively, the
 * "License"). You may not use this file except in compliance with the
 * License. You can obtain a copy of the License at
 * https://netbeans.org/cddl-gplv2.html or
 * nbbuild/licenses/CDDL-GPL-2-CP. See the License for the specific
 * language governing permissions and limitations under the License.
 * When distributing the software, include this License Header
 * Notice in each file and include the License file at
 * nbbuild/licenses/CDDL-GPL-2-CP. Oracle designates this particular file
 * as subject to the "Classpath" exception as provided by Oracle in the
 * GPL Version 2 section of the License file that accompanied this code. If
 * applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyrighted [year] [name of copyright owner]"
 * <p>
 * Contributor(s):
 * Created by alejandro tkachuk @aletkachuk
 * www.calculistik.com
 */
public class HttpRequest {

    public static enum Method {
        POST, PUT, DELETE, GET;
    }

    private URL url;
    private HttpURLConnection connection;
    private OutputStream outputStream;
    private HashMap<String, String> params = new HashMap<String, String>();

    public HttpRequest(String url) throws IOException {
        this.url = new URL(url);
        connection = (HttpURLConnection) this.url.openConnection();
    }

    public int get() throws IOException {
        return this.send();
    }

    public int post(String data) throws IOException {
        connection.setDoInput(true);
        connection.setRequestMethod(Method.POST.toString());
        connection.setDoOutput(true);
        outputStream = connection.getOutputStream();
        this.sendData(data);
        return this.send();
    }

    public int post() throws IOException {
        connection.setDoInput(true);
        connection.setRequestMethod(Method.POST.toString());
        connection.setDoOutput(true);
        outputStream = connection.getOutputStream();
        return this.send();
    }

    public int put(String data) throws IOException {
        connection.setDoInput(true);
        connection.setRequestMethod(Method.PUT.toString());
        connection.setDoOutput(true);
        outputStream = connection.getOutputStream();
        this.sendData(data);
        return this.send();
    }

    public int put() throws IOException {
        connection.setDoInput(true);
        connection.setRequestMethod(Method.PUT.toString());
        connection.setDoOutput(true);
        outputStream = connection.getOutputStream();
        return this.send();
    }

    public HttpRequest addHeader(String key, String value) {
        connection.setRequestProperty(key, value);
        return this;
    }

    public HttpRequest addParameter(String key, String value) {
        this.params.put(key, value);
        return this;
    }

    public JSONObject getJSONObjectResponse() throws JSONException, IOException {
        return new JSONObject(getStringResponse());
    }

    public JSONArray getJSONArrayResponse() throws JSONException, IOException {
        return new JSONArray(getStringResponse());
    }

    public String getStringResponse() throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        StringBuilder response = new StringBuilder();
        for (String line; (line = br.readLine()) != null; ) response.append(line + "\n");
        return response.toString();
    }

    public byte[] getBytesResponse() throws IOException {
        byte[] buffer = new byte[8192];
        InputStream is = connection.getInputStream();
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        for (int bytesRead; (bytesRead = is.read(buffer)) >= 0; )
            output.write(buffer, 0, bytesRead);
        return output.toByteArray();
    }

    public void close() {
        if (null != connection)
            connection.disconnect();
    }

    private int send() throws IOException {
        int httpStatusCode = HttpURLConnection.HTTP_BAD_REQUEST;

        if (!this.params.isEmpty()) {
            this.sendData();
        }
        httpStatusCode = connection.getResponseCode();

        return httpStatusCode;
    }

    private void sendData() throws IOException {
        StringBuilder result = new StringBuilder();
        for (Map.Entry<String, String> entry : params.entrySet()) {
            result.append((result.length() > 0 ? "&" : "") + entry.getKey() + "=" + entry.getValue());//appends: key=value (for first param) OR &key=value(second and more)
        }
        sendData(result.toString());
    }

    private HttpRequest sendData(String query) throws IOException {
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
        writer.write(query);
        writer.close();
        return this;
    }

}

适用于android API 28及更高版本 在Manifest.xml应用程序标签内

    <application
    .
    .
    .

    <uses-library android:name="org.apache.http.legacy" android:required="false"/>