在Java的Jersey框架中,實(shí)現(xiàn)緩存機(jī)制可以通過(guò)使用HTTP緩存頭來(lái)完成。這些緩存頭包括:Cache-Control、ETag、Last-Modified等。以下是一個(gè)簡(jiǎn)單的示例,展示了如何在Jersey中實(shí)現(xiàn)緩存機(jī)制:
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.CacheControl;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.EntityTag;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.Response;
@Path("/cached")
public class CachedResource {
private static final String RESOURCE_DATA = "This is the cached data.";
private static final EntityTag ETAG = new EntityTag(Integer.toString(RESOURCE_DATA.hashCode()));
@GET
@Produces("text/plain")
public Response getCachedData(@Context Request request) {
// 檢查請(qǐng)求中的ETag
Response.ResponseBuilder responseBuilder = request.evaluatePreconditions(ETAG);
if (responseBuilder == null) {
// 如果ETag不匹配,則返回?cái)?shù)據(jù)和新的ETag
CacheControl cacheControl = new CacheControl();
cacheControl.setMaxAge(60); // 設(shè)置緩存時(shí)間為60秒
responseBuilder = Response.ok(RESOURCE_DATA)
.cacheControl(cacheControl)
.tag(ETAG);
} else {
// 如果ETag匹配,則返回304 Not Modified
responseBuilder = responseBuilder.status(Response.Status.NOT_MODIFIED);
}
return responseBuilder.build();
}
}
import org.glassfish.jersey.server.ResourceConfig;
public class MyApplication extends ResourceConfig {
public MyApplication() {
register(CachedResource.class);
}
}
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet</artifactId>
<version>2.30.1</version>
</dependency><dependency>
<groupId>org.glassfish.jersey.core</groupId>
<artifactId>jersey-server</artifactId>
<version>2.30.1</version>
</dependency>
現(xiàn)在,當(dāng)客戶端請(qǐng)求/cached
路徑時(shí),服務(wù)器將返回緩存的數(shù)據(jù)。客戶端可以通過(guò)發(fā)送帶有If-None-Match頭的請(qǐng)求來(lái)驗(yàn)證緩存的數(shù)據(jù)是否仍然是最新的。如果數(shù)據(jù)未更改,服務(wù)器將返回304 Not Modified狀態(tài)碼,客戶端可以使用本地緩存的數(shù)據(jù)。