Okhttp session持久化

直接上HttpEngine的部分源码

public void receiveHeaders(Headers headers) throws IOException {
if (client.cookieJar() == CookieJar.NO_COOKIES) return;

List<Cookie> cookies = Cookie.parseAll(userRequest.url(), headers);if (cookies.isEmpty()) return;client.cookieJar().saveFromResponse(userRequest.url(), cookies);

}

/**
* Populates request with defaults and cookies.
*
*

This client doesn’t specify a default {@code Accept} header because it doesn’t know what
* content types the application is interested in.
*/
private Request networkRequest(Request request) throws IOException {
Request.Builder result = request.newBuilder();

if (request.header("Host") == null) {  result.header("Host", hostHeader(request.url(), false));}if (request.header("Connection") == null) {  result.header("Connection", "Keep-Alive");}if (request.header("Accept-Encoding") == null) {  transparentGzip = true;  result.header("Accept-Encoding", "gzip");}List<Cookie> cookies = client.cookieJar().loadForRequest(request.url());if (!cookies.isEmpty()) {  result.header("Cookie", cookieHeader(cookies));}if (request.header("User-Agent") == null) {  result.header("User-Agent", Version.userAgent());}return result.build();

}

/* Returns a ‘Cookie’ HTTP request header with all cookies, like {@code a=b; c=d}. /
private String cookieHeader(List cookies) {
StringBuilder cookieHeader = new StringBuilder();
for (int i = 0, size = cookies.size(); i < size; i++) {
if (i > 0) {
cookieHeader.append(“; “);
}
Cookie cookie = cookies.get(i);
cookieHeader.append(cookie.name()).append(‘=’).append(cookie.value());
}
return cookieHeader.toString();
}

也就是在发送请求的时候Okhttp会在networkRequest()方法中通过client.cookieJar().loadForRequest(request.url())加载我们自己保存的cookie，然后通过 result.header(“Cookie”, cookieHeader(cookies));为header添加Cookie，cookieHeader()方法主要是实现name=value;的形式。所以loadForRequest()方法很重要。

然后在接收响应的时候，Okhttp会在receiveHeaders()方法中通过client.cookieJar().saveFromResponse()方法保存响应返回的cookie。

总结一下，也就是通过cookieJar为媒介为Okhttp添加和保存cookie。其中loadForRequest()加载已经保存过的cookie，saveFromResponse()保存响应时的cookie。