Okhttp教程 (1)

1. 在build.gradle里引入okhttp库

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:24.2.0'
    compile 'com.squareup.okhttp:okhttp:2.4.0'
    compile 'com.google.code.gson:gson:2.6.2'
}

2. 创建okhttp对象，这里是用赖汉模式，减少系统的记忆体消耗。

public class OkHttp {

    // okHttp
    private static OkHttpClient okHttpClient;

    // 饿汉式
    private static OkHttp okHttp = new OkHttp();

    private OkHttp(){}

    public static OkHttp getInstance(){
        okHttpClient = new OkHttpClient();
        return okHttp;
    }
}

3. 在okhttp对象里创建getResponse方法，返回服务器的回应。

    // 取得數據
    private Request request;
    private Response response;
    private String strContext;
    public String getResponse(String strURL) {
        try {
            // 创建okhttp Builder，从URL返回服务器的回应
            request = new Request.Builder()
                    .url(strURL)
                    .build();
            // response储存服务器的回应
            response = okHttpClient.newCall(request).execute();
            // 把response转换成string
            strContext = response.body().string();
        }catch (IOException e) {
            strContext = e.toString();
        }
        return strContext;
    }

4. 如果是想利用okhttp上传文件，可用uploadImage方法。

    // 上傳圖片
    private String uploadResult;
    public String uploadImage(String URL, String userId, File file, String fileName) {
        try {
            // MultipartBuilder，是上传文件的query
            // addFormDataPart方法：@param [String]name, [String]value
            // addFormDataPart方法：@param [String]name, [String]fileName, [String]fileType, [String]file
            RequestBody requestBody = new MultipartBuilder()
                    .type(MultipartBuilder.FORM)
                    .addFormDataPart("portrait", fileName,
                            RequestBody.create(MediaType.parse("image/jpg"), file))
                    .addFormDataPart("userId", userId)
                    .addFormDataPart("action", "updateProtrait")
                    .build();

            // request方法： @param [String]URL, [RequestBody]requestBody
            Request request = new Request.Builder()
                    .url(URL)
                    .post(requestBody)
                    .build();

            // response储存服务器的回应
            Response response = okHttpClient.newCall(request).execute();
            // 把response转换成string
            uploadResult = response.body().string();

        } catch (IOException e) {
            uploadResult = e.toString();
        }
        return uploadResult;
    }