玩转mongodb（三）：mongodb项目实战（初战）

    主要功能：对mongoDB的集合做增删改查。

    项目的运行环境：tomcat6、jdk8。

    所用技术：mongoDB、jsp/servlet、前端bootstrap。

    定义一个MongoDBUtil的枚举类，枚举类中定义一个instance实例。

    MongoDB工具类 Mongo实例代表了一个数据库连接池，即使在多线程的环境中，一个Mongo实例对我们来说已经足够。

    注意Mongo已经实现了连接池，并且是线程安全的。

    设计为单例模式， 因 MongoDB的Java驱动是线程安全的，对于一般的应用，只要一个Mongo实例即可。

    Mongo有个内置的连接池（默认为10个） 对于有大量写和读的环境中，为了确保在一个Session中使用同一个DB时，DB和DBCollection是绝对线程安全的。

public enum MongoDBUtil {
    /**
     * 定义一个枚举的元素，它代表此类的一个实例
     */
    instance;
}

    在MongoDBUtil类中，定义一个MongoClient对象，并根据IP和端口获得该对象。

private MongoClient mongoClient;
static {
    System.out.println("===MongoDBUtil初始化===");
    // 从配置文件中获取属性值
    String ip = "localhost";
    int port = 27017;
    instance.mongoClient = new MongoClient(ip, port);
}

    根据MongoClient对象，得到MongoDataBase对象和MongoConnection<Document>对象。

/**
     * 获取DB实例 - 指定DB
     * 
     * @param dbName
     * @return
     */
    public MongoDatabase getDB(String dbName) {
        if (dbName != null && !"".equals(dbName)) {
            MongoDatabase database = mongoClient.getDatabase(dbName);
            return database;
        }
        return null;
    }
    /**
     * 获取collection对象 - 指定Collection
     * 
     * @param collName
     * @return
     */
    public MongoCollection<Document> getCollection(String dbName, String collName) {
        if (null == collName || "".equals(collName)) {
            return null;
        }
        if (null == dbName || "".equals(dbName)) {
            return null;
        }
        MongoCollection<Document> collection = mongoClient.getDatabase(dbName).getCollection(collName);
        return collection;
    }

    工具类的查询、插入、更新、删除方法。

/**条件查询*/
public MongoCursor<Document> find(MongoCollection<Document> coll, Bson filter) {
    if(null!=filter){
        return coll.find(filter).iterator();
    }else{
        return coll.find().iterator();
    }
}
/**插入一条数据*/
public void insert(MongoCollection<Document> coll,Document doc){
    coll.insertOne(doc);
}
/**更新一条数据*/
public void update(MongoCollection<Document> coll,Document querydoc,Document updatedoc){
    coll.updateMany(querydoc, updatedoc);
}
/**删除一条数据*/
public void delete(MongoCollection<Document> coll,Document doc){
    coll.deleteMany(doc);
}

    插入功能的servlet

String name = request.getParameter("name");
Double age = Double.valueOf(request.getParameter("age"));
String dbName = "personmap";
String collName = "person";
MongoCollection<Document> coll = MongoDBUtil.instance.getCollection(dbName, collName);
Document doc = new Document();
doc.put("name", name);
doc.put("age", age);
MongoDBUtil.instance.insert(coll, doc);
PrintWriter out = response.getWriter();
out.write("insert success!");

    插入功能的jsp

<div class="panel    panel-warning" style="width:20%">
    <div class="panel-heading">删除文档</div>
    <div class="panel-body">
        <form action="InsertPerson">
            <input type="text" name="name" class="form-control" placeholder="name" aria-describedby="basic-addon1">
            <br/>
            <input type="text" name="age" class="form-control" placeholder="age" aria-describedby="basic-addon1">
            <br/>
            <button type="submit" class="btn btn-default">插入</button>
        </form>
    </div>
</div>

    更新功能的servlet

String queryname = request.getParameter("queryname");
Double updateage = Double.valueOf(request.getParameter("updateage"));
String dbName = "personmap";
String collName = "person";
MongoCollection<Document> coll = MongoDBUtil.instance.getCollection(dbName, collName);
Document querydoc = new Document();
querydoc.put("name", queryname);
Document updatedoc = new Document();
updatedoc.put("name", queryname);
updatedoc.put("age", updateage);
MongoDBUtil.instance.update(coll, querydoc , new Document("$set",updatedoc));
PrintWriter out = response.getWriter();
out.write("update success!");

    更新功能的jsp

<div class="panel    panel-warning" style="width:20%">
    <div class="panel-heading">根据name更新age</div>
    <div class="panel-body">
        <form action="UpdatePerson">
            <input type="text" name="queryname" class="form-control" placeholder="queryname" aria-describedby="basic-addon1">
            <br/>
            <input type="text" name="updateage" class="form-control" placeholder="updateage" aria-describedby="basic-addon1">
            <br/>
            <button type="submit" class="btn btn-default">更新</button>
    </form>
    </div>
</div>

    删除功能的servlet

String name = request.getParameter("name");
String dbName = "personmap";    
String collName = "person";
MongoCollection<Document> coll = MongoDBUtil.instance.getCollection(dbName, collName);
Document doc = new Document();
doc.put("name", name);
MongoDBUtil.instance.delete(coll, doc);
PrintWriter out = response.getWriter();
out.write("delete success!");

    删除功能的jsp

<div class="panel    panel-warning" style="width:20%">
    <div class="panel-heading">删除文档</div>
    <div class="panel-body">
        <form action="DeletePerson">
            <input type="text" name="name" class="form-control" placeholder="name" aria-describedby="basic-addon1">
            <br/>
            <button type="submit" class="btn btn-default">删除</button>
        </form>
    </div>
</div>

    **查找**：对应MongoDB中脚本的db.getCollection('person').find({})

    查找功能的servlet

String dbName = "personmap";
String collName = "person";
MongoCollection<Document> coll = MongoDBUtil.instance.getCollection(dbName, collName);
List<Person> personList = new ArrayList<Person>();
// 查询所有
//Bson filter = Filters.eq("name", "ryan1");
Bson filter = null;
MongoCursor<Document> cursor = MongoDBUtil.instance.find(coll, filter);
while(cursor.hasNext()){
    Document tempdoc = cursor.next();
    Person person = new Person();
    person.set_id(tempdoc.get("_id").toString());
    person.setName(tempdoc.get("name").toString());
person.setAge(Double.valueOf(tempdoc.get("age").toString()));
    personList.add(person);
}
Gson gson = new Gson();
PrintWriter out = response.getWriter();
out.write(gson.toJson(personList));

    查找功能的jsp

<div class="panel panel-warning" style="width:50%">
    <div class="panel-heading">查找全部数据</div>
    <div class="panel-body">
    <table data-toggle="table" 
               data-url="FindPerson"
               data-classes="table table-hover table-condensed"
               data-striped="true">
        <thead>
            <tr>
                <th class="col-xs-2" data-field="_id">_id</th>
                <th class="col-xs-2" data-field="name">name</th>
                <th class="col-xs-2" data-field="age">age</th>
            </tr>
        </thead>
    </table>
    </div>
</div>