编程笔记-- Coolder.com

上一篇：下载Eclipse的链接
下一篇：加拿大买卖房的几个网站，备份一下，买房时可能用的上

一个简单的使用Google DataStore的例子

米娅 2012年1月31日 14:02:42

java 文件

import java.util.Date;
import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.KeyFactory;
import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.EntityNotFoundException;
import java.io.IOException;

public class DataStore {

    DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
    Date putDate = new Date();
    Entity entity = null;
    String links = "";

public String createEntity(String headlines, String entity_key) {

entity = new Entity(headlines, entity_key);

        entity.setProperty("Name", null);
        entity.setProperty("Link", null);
        entity.setProperty("Date", putDate);
        entity.setProperty("Description", null);
        datastore.put(entity);

return "create";
}

public String updateEntity(Key entity_key, String name, String link, String description) {

try {
entity = datastore.get(entity_key);

            entity.setProperty("Name", name);
            entity.setProperty("Link", link);
            entity.setProperty("Date", putDate);
            entity.setProperty("Description", description);

datastore.put(entity);

} catch (EntityNotFoundException e) {
}

return "update";
}

public String deleteEntity(Key entity_key) {

        datastore.delete(entity_key);
        return "delete";
    }

public String getPropertiesOfEntity(Key entity_key) {

try {

            entity = datastore.get(entity_key);
            String media_name = (String) entity.getProperty("Name");
            String news_links = (String) entity.getProperty("Link");

links = media_name + news_links;

} catch (EntityNotFoundException e) {
}

return "get" + links;
}

public String getLinks() {

String key_str = "H";

Key entity_key = KeyFactory.createKey("Headlines", key_str);

        //       createEntity("Headlines", key_str);
        //       updateEntity(entity_key, "1", "2", "3");
        //     deleteEntity(entity_key);

return "Well done" + getPropertiesOfEntity(entity_key);
}
}

jsp文件：

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@ page import="DataStore" %>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <h1>Hello World!</h1>

DataStore Database = new DataStore();

<%= Database.getLinks() %>

</body>
</html>

共1页