一 OkHttp介绍
OkHttp是一个优秀的网络请求框架，目前主流已经替换httpclient, HttpURLConnection 使用方式；
OkHttp支持连接同一地址的链接共享同一个socket，通过连接池来减小响应延迟，自带GZIP压缩，请求缓存等优势；
OkHttp 成为 Android 最常见的网络请求库, 但并不妨碍java后端学习他，所以这边知识追寻者 做了常用总结
github: https://github.com/square/okhttp
官方文档：https://square.github.io/okhttp/
二 依赖
目前最新版本：4.9.0
maven
<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
<version>3.6.0</version>
</dependency>
gradle
compile 'com.squareup.okhttp3:okhttp:3.6.0'
三 GET 请求
请求步骤
- 获取OkHttpClient对象
- 设置请求request
- 封装call
- 异步调用,并设置回调函数
/**
* @Author lsc
* <p>get 请求 </p>
* @Param [url]
* @Return
*/
public void get(String url){
// 1 获取OkHttpClient对象
OkHttpClient client = new OkHttpClient();
// 2设置请求
Request request = new Request.Builder()
.get()
.url(url)
.build();
// 3封装call
Call call = client.newCall(request);
// 4异步调用,并设置回调函数
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
// ...
}
@Override
public void onResponse(Call call, final Response response) throws IOException {
if (response!=null && response.isSuccessful()){
// ...
// response.body().string();
}
}
});
//同步调用,返回Response,会抛出IO异常
//Response response = call.execute();
}
四 POST 请求
4.1 form 表单形式
- 获取OkHttpClient对象
- 构建参数body
- 构建 request
- 将Request封装为Call
- 异步调用
/**
* @Author lsc
* <p> post 请求， form 参数</p>
* @Param [url]
* @Return
*/
public void postFormData(String url){
// 1 获取OkHttpClient对象
OkHttpClient client = new OkHttpClient();
// 2 构建参数
FormBody formBody = new FormBody.Builder()
.add("username", "admin")
.add("password", "admin")
.build();
// 3 构建 request
Request request = new Request.Builder()
.url(url)
.post(formBody)
.build();
// 4 将Request封装为Call
Call call = client.newCall(request);
// 5 异步调用
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
// ...
}
@Override
public void onResponse(Call call, final Response response) throws IOException {
if (response!=null && response.isSuccessful()){
// ...
}
}
});
}
4.2 json参数形式
- 获取OkHttpClient对象
- 构建参数
- 构建 request
- 将Request封装为Call
- 异步调用
/**
* @Author lsc
* <p>post 请求 ，json参数 </p>
* @Param [url, json]
* @Return
*/
public void postForJson(String url, String json){
// 1 获取OkHttpClient对象
OkHttpClient client = new OkHttpClient();
// 2 构建参数
RequestBody requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), json);
// 3 构建 request
Request request = new Request.Builder()
.url(url)
.post(requestBody)
.build();
// 4 将Request封装为Call
Call call = client.newCall(request);
// 5 异步调用
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
// ...
}
@Override
public void onResponse(Call call, final Response response) throws IOException {
if (response!=null && response.isSuccessful()){
// ...
}
}
});
}
如果是json字符串，替换请求媒体类型即可
// 2 构建参数
RequestBody requestBody = RequestBody.create(MediaType.parse("text/plain;charset=utf-8"), "{username:admin;password:admin}");
// 3 构建 request
Request request = new Request.Builder()
.url(url)
.post(requestBody)
.build();
4.3 文件下载
- 获取OkHttpClient对象
- 构建 request
- 异步调用
- 文件下载
/**
* @Author lsc
* <p> 文件下载 </p>
* @Param url 下载地址url
* @Param target 下载目录
* @Param target 文件名
* @Return
*/
private void download(String url, String target, String fileName){
// 1 获取OkHttpClient对象
OkHttpClient client = new OkHttpClient();
// 2构建 request
Request request = new Request.Builder()
.url(url)
.build();
// 3 异步调用
client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
e.printStackTrace();
}
@Override
public void onResponse(Call call, Response response) throws IOException {
if (response.isSuccessful()){
// 4 文件下载
downlodefile(response, target,fileName);
}
}
});
}
private void downlodefile(Response response, String url, String fileName) {
InputStream inputStream = null;
byte[] buf = new byte[2048];
int len = 0;
FileOutputStream outputStream = null;
try {
inputStream = response.body().byteStream();
//文件大小
long total = response.body().contentLength();
File file = new File(url, fileName);
outputStream = new FileOutputStream(file);
long sum = 0;
while ((len = inputStream.read(buf)) != -1) {
outputStream.write(buf, 0, len);
}
outputStream.flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (inputStream != null)
inputStream.close();
if (outputStream != null)
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
4.4 文件上传
- 获取OkHttpClient对象
- 封装参数以 form形式, 媒体格式为二进制流
- 封装 request
- 异步回调
/**
* @Author lsc
* <p> 文件上传 </p>
* @Param [url]
* @Return
*/
public void upload(String url){
File file = new File("C:/mydata/generator/test.txt");
if (!file.exists()){
System.out.println("文件不存在");
}else{
// 获取OkHttpClient对象
OkHttpClient client = new OkHttpClient();
// 2封装参数以 form形式
RequestBody requestBody = new MultipartBody.Builder()
.setType(MultipartBody.FORM)
.addFormDataPart("username", "admin")
.addFormDataPart("password", "admin")
.addFormDataPart("file", "555.txt", RequestBody.create(MediaType.parse("application/octet-stream"), file))
.build();
// 3 封装 request
Request request = new Request.Builder()
.url(url)
.post(requestBody)
.build();
// 4 异步回调
client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
e.printStackTrace();
}
@Override
public void onResponse(Call call, Response response) throws IOException {
}
});
}
}
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