Retrofit全攻略——进阶篇
最近事比较多，距离上次写文章已经过去了一个月了。上一篇文章 Retrofit全攻略——基础篇 介绍了Retrofit的基础用法，这篇文章介绍点进阶的用法。
打印网络日志
在开发阶段，为了方便调试，我们需要查看网络日志。因为 Retrofit2.0+底层是采用的 OKHttp请求的。可以给OKHttp设置拦截器，用来打印日志。
首先可以在 app/build.gradle中添加依赖，这是官方的日志拦截器。
compile 'com.squareup.okhttp3:logging-interceptor:3.3.0'
然后在代码中设置：
public static Retrofit getRetrofit() {
//如果mRetrofit为空 或者服务器地址改变 重新创建
if (mRetrofit == null) {
OkHttpClient httpClient;
OkHttpClient.Builder builder=new OkHttpClient.Builder();
//阶段分为开发和发布阶段，当前为开发阶段设置拦截器
if (BuildConfig.DEBUG) {
HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
//设置拦截器级别
logging.setLevel(HttpLoggingInterceptor.Level.BODY);
builder.addInterceptor(logging);
}
httpClient=builder.build();
//构建Retrofit
mRetrofit = new Retrofit.Builder()
//配置服务器路径
.baseUrl(mServerUrl)
//返回的数据通过Gson解析
.addConverterFactory(GsonConverterFactory.create())
//配置回调库，采用RxJava
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
//设置OKHttp模板
.client(httpClient)
.build();
}
return mRetrofit;
}
当处于开发阶段的时候，设置监听日志的拦截器。拦截有4个级别，分别是
- BODY
- HEADERS
- BASIC
- NONE
其中 BODY输出的日志是最全的。
添加相同的请求参数
为了更好的管理迭代版本，一般每次发起请求的时候都传输当前程序的版本号到服务器。
有些项目我们每次还会传用户id，token令牌等相同的参数。
如果在每个请求的接口都添加这些参数太繁琐。Retrofit可以通过拦截器添加相同的请求参数，无需再每个接口添加了。
步骤一，自己拦截器
public class CommonInterceptor implements Interceptor {
@Override
public Response intercept(Interceptor.Chain chain) throws IOException {
Request oldRequest = chain.request();
// 添加新的参数
HttpUrl.Builder authorizedUrlBuilder = oldRequest.url()
.newBuilder()
.scheme(oldRequest.url().scheme())
.host(oldRequest.url().host())
.addQueryParameter("device_type", "1")
.addQueryParameter("version", BuildConfig.VERSION_NAME)
.addQueryParameter("token", PreUtils.getString(R.string.token))
.addQueryParameter("userid", PreUtils.getString(R.string.user_id));
// 新的请求
Request newRequest = oldRequest.newBuilder()
.method(oldRequest.method(), oldRequest.body())
.url(authorizedUrlBuilder.build())
.build();
return chain.proceed(newRequest);
}
}
实现原理就是拦截之前的请求，添加完参数，再传递新的请求。这个位置我添加了四个公共的参数。
然后再Retrofit初始化的时候配置。
if (mRetrofit == null) {
OkHttpClient httpClient;
OkHttpClient.Builder builder=new OkHttpClient.Builder();
//添加公共参数
builder.addInterceptor(new CommonInterceptor());
httpClient=builder.build();
//构建Retrofit
mRetrofit = new Retrofit.Builder()
//....
.client(httpClient)
.build();
}
处理约定错误
除了常见的404，500等异常，网络请求中我们往往还会约定些异常，比如token失效，账号异常等等。
以token失效为例，每次请求我们都需要验证是否失效，如果在每个接口都处理一遍错误就有点太繁琐了。
我们可以统一处理下错误。
步骤一，Retrofit初始化时添加自定义转化器
mRetrofit = new Retrofit.Builder()
//配置服务器路径
baseUrl(mServerUrl)
//配置回调库，采用RxJava
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
//配置转化库，默认是Gson，这里修改了。
.addConverterFactory(ResponseConverterFactory.create())
.client(httpClient)
.build();
步骤二 创建ResponseConverterFactory
步骤一 ResponseConverterFactory这个类是需要我们自己创建的。
public class ResponseConverterFactory extends Converter.Factory {
/**
* Create an instance using a default {@link Gson} instance for conversion. Encoding to JSON and
* decoding from JSON (when no charset is specified by a header) will use UTF-8.
*/
public static ResponseConverterFactory create() {
return create(new Gson());
}
/**
* Create an instance using {@code gson} for conversion. Encoding to JSON and
* decoding from JSON (when no charset is specified by a header) will use UTF-8.
*/
public static ResponseConverterFactory create(Gson gson) {
return new ResponseConverterFactory(gson);
}
private final Gson gson;
private ResponseConverterFactory(Gson gson) {
if (gson == null) throw new NullPointerException("gson == null");
this.gson = gson;
}
@Override
public Converter<ResponseBody, ?> responseBodyConverter(Type type, Annotation[] annotations,
Retrofit retrofit) {
// TypeAdapter<?> adapter = gson.getAdapter(TypeToken.get(type));
return new GsonResponseBodyConverter<>(gson, type);
}
@Override
public Converter<?, RequestBody> requestBodyConverter(Type type,
Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) {
TypeAdapter<?> adapter = gson.getAdapter(TypeToken.get(type));
return new GsonRequestBodyConverter<>(gson, adapter);
}
}
这里面我们自定义了请求和响应时解析JSON的转换器—— GsonRequestBodyConverter和 GsonResponseBodyConverter。
其中 GsonRequestBodyConverter 负责处理请求时传递JSON对象的格式，不需要额外处理任何事，直接使用默认的GSON解析。代码我直接贴出来：
final class GsonRequestBodyConverter<T> implements Converter<T, RequestBody> {
private static final MediaType MEDIA_TYPE = MediaType.parse("application/json; charset=UTF-8");
private static final Charset UTF_8 = Charset.forName("UTF-8");
private final Gson gson;
private final TypeAdapter<T> adapter;
GsonRequestBodyConverter(Gson gson, TypeAdapter<T> adapter) {
this.gson = gson;
this.adapter = adapter;
}
@Override public RequestBody convert(T value) throws IOException {
Buffer buffer = new Buffer();
Writer writer = new OutputStreamWriter(buffer.outputStream(), UTF_8);
JsonWriter jsonWriter = gson.newJsonWriter(writer);
adapter.write(jsonWriter, value);
jsonWriter.close();
return RequestBody.create(MEDIA_TYPE, buffer.readByteString());
}
}
GsonResponseBodyConverter负责把响应的数据转换成JSON格式，这个我们需要处理一下。
public class GsonResponseBodyConverter<T> implements Converter<ResponseBody, T> {
private final Gson gson;
private final Type type;
GsonResponseBodyConverter(Gson gson, Type type) {
this.gson = gson;
this.type = type;
}
@Override
public T convert(ResponseBody value) throws IOException {
String response = value.string();
try {
Log.i("YLlibrary", "response>>> "+response);
//ResultResponse 只解析result字段
BaseInfo baseInfo = gson.fromJson(response, BaseInfo.class);
if (baseInfo.getHeader().getCode().equals("1")) {
//正确
return gson.fromJson(response, type);
} else {
//ErrResponse 将msg解析为异常消息文本 错误码可以自己指定.
throw new ResultException(-1024, baseInfo,response);
}
} finally {
}
}
}
这种情况只是应用于后台接口数据统一的情况。比如我们项目的格式是这样的
{
header : {"message":"token失效","code":"99"}
data : {}
}
当code值是1的时候，表示正确，其它数字表示错误。只有正确的时候data才会有内容。
这里我用BaseInfo解析这个JSON：
public class BaseInfo {
/**
* header : {"message":"用户名或密码错误","code":"0"}
* data : {}
*/
private HeaderBean header;
public HeaderBean getHeader() {
return header;
}
public void setHeader(HeaderBean header) {
this.header = header;
}
public static class HeaderBean {
/**
* message : 用户名或密码错误
* code : 0
*/
private String message;
private String code;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
}
}
服务器返回的数据实体对象全部继承 BaseInfo 只是data内容不一样。
ResultException这个类用于捕获服务器约定的错误类型
/**
* 这个类用于捕获服务器约定的错误类型
*/
public class ResultException extends RuntimeException {
private int errCode = 0;
private BaseInfo info;
private String response;
public ResultException(int errCode, BaseInfo info,String response) {
super(info.getHeader().getMessage());
this.info=info;
this.errCode = errCode;
this.response=response;
}
public String getResponse() {
return response;
}
public void setResponse(String response) {
this.response = response;
}
public int getErrCode() {
return errCode;
}
public BaseInfo getBaseInfo(){
return info;
}
}
最后定义Retrofit处理异常的代码
public abstract class AbsAPICallback<T> extends Subscriber<T> {
//对应HTTP的状态码
private static final int UNAUTHORIZED = 401;
private static final int FORBIDDEN = 403;
private static final int NOT_FOUND = 404;
private static final int REQUEST_TIMEOUT = 408;
private static final int INTERNAL_SERVER_ERROR = 500;
private static final int BAD_GATEWAY = 502;
private static final int SERVICE_UNAVAILABLE = 503;
private static final int GATEWAY_TIMEOUT = 504;
//出错提示
private final String networkMsg;
private final String parseMsg;
private final String unknownMsg;
protected AbsAPICallback(String networkMsg, String parseMsg, String unknownMsg) {
this.networkMsg = networkMsg;
this.parseMsg = parseMsg;
this.unknownMsg = unknownMsg;
}
public AbsAPICallback(){
networkMsg="net error(联网失败)";
parseMsg="json parser error(JSON解析失败)";
unknownMsg="unknown error(未知错误)";
}
ProgressBar progressBar;
public AbsAPICallback(ProgressBar progressBar){
this();
this.progressBar=progressBar;
}
@Override
public void onError(Throwable e) {
Throwable throwable = e;
//获取最根源的异常
while(throwable.getCause() != null){
e = throwable;
throwable = throwable.getCause();
}
ApiException ex;
if (e instanceof HttpException){ //HTTP错误
HttpException httpException = (HttpException) e;
ex = new ApiException(e, httpException.code());
switch(httpException.code()){
case UNAUTHORIZED:
case FORBIDDEN:
// onPermissionError(ex); //权限错误，需要实现
// break;
case NOT_FOUND:
case REQUEST_TIMEOUT:
case GATEWAY_TIMEOUT:
case INTERNAL_SERVER_ERROR:
case BAD_GATEWAY:
case SERVICE_UNAVAILABLE:
default:
ex.setDisplayMessage(networkMsg); //均视为网络错误
onNetError(ex);
break;
}
} else if (e instanceof ResultException){ //服务器返回的错误
ResultException resultException = (ResultException) e;
onResultError(resultException);
} else if (e instanceof JsonParseException
|| e instanceof JSONException
|| e instanceof ParseException){
ex = new ApiException(e, ApiException.PARSE_ERROR);
ex.setDisplayMessage(parseMsg); //均视为解析错误
onNetError(ex);
} else {
ex = new ApiException(e, ApiException.UNKNOWN);
ex.setDisplayMessage(unknownMsg); //未知错误
onNetError(ex);
}
}
static long time;
protected void onNetError(ApiException e){
long currentTime=System.currentTimeMillis();
if(currentTime-time>3000){ //防止连续反馈
time=currentTime;
UIUtils.showToast("网络加载失败");
}
e.printStackTrace();
onApiError(e);
}
/**
* 错误回调
*/
protected void onApiError(ApiException ex){
Log.i("YLLibrary","onApiError");
if(progressBar!=null)
UIUtils.runOnUiThread(new Runnable() {
@Override
public void run() {
progressBar.setVisibility(View.GONE);
progressBar=null;
}
});
}
// /**
// * 权限错误，需要实现重新登录操作
// */
// protected void onPermissionError(ApiException ex){
// ex.printStackTrace();
// }
/**
* 服务器返回的错误
*/
protected synchronized void onResultError(ResultException ex){
// if(ex.getErrCode()== XApplication.API_ERROR){
// UIUtils.getContext().onApiError(); //可以用来处理Token失效
// return ;
// }
if(ConstantValue.TOKEN_ERROR.equals(ex.getBaseInfo().getHeader().getCode())
&&!TextUtils.isEmpty(PreUtils.getString(R.string.token))){ //验证token是否为空是为了防止连续两次请求
PreUtils.putString(R.string.user_id,null);
PreUtils.putString(R.string.token,null);
PreUtils.putString(R.string.orgDistrict,null);
if(BaseActivity.runActivity!=null){
Intent intent = new Intent(UIUtils.getContext(), LoginActivity.class);
if(BaseActivity.runActivity instanceof MainActivity){
MainActivity activity= (MainActivity) BaseActivity.runActivity;
int tabIndex=activity.getCurrentTab();
//activity.switchCurrentTab(0);
activity.startActivityForResult(intent,tabIndex+10);
}else {
BaseActivity.runActivity.startActivity(intent);
}
}
}
Log.i("YLLibrary","resultError");
if(ex.getBaseInfo()!=null&&!TextUtils.isEmpty(ex.getBaseInfo().getHeader().getMessage()))
UIUtils.showToast(ex.getBaseInfo().getHeader().getMessage());
ApiException apiException = new ApiException(ex, ex.getErrCode());
onApiError(apiException);
}
@Override
public void onCompleted() {
Log.i("YLLibrary","onCompleted");
if(progressBar!=null)
UIUtils.runOnUiThread(new Runnable() {
@Override
public void run() {
progressBar.setVisibility(View.GONE);
progressBar=null;
}
});
}
}
实际接口请求的代码，使用自定义异常回调的类—— AbsAPICallback就可以统一处理异常:
ApiRequestManager.createApi().problemDetail(dataBean.getId())
.compose(ApiRequestManager.<QuestionDetailInfo>applySchedulers())
.subscribe(new AbsAPICallback<QuestionDetailInfo>() {
@Override
public void onNext(QuestionDetailInfo baseInfo) {
fillData(baseInfo);
}
});
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作者：yulianlin 发表于2017/3/9 8:51:26 原文链接
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