EasyUI实现异步加载tree(整合Struts2)

首先jsp页面有一ul用于展现Tree

<ul id="mytree"></ul>

加载Tree

<script type="text/javascript">

	$('#mytree').tree({

	    url:'treeLoad.action'

	});

</script>

配置Action

<struts>

	<package name="tree_json" extends="json-default">

		<action name="treeLoad" method="treeLoad" class="com.home.web.TreeAction">

			<result type="json">

				<param name="root">treeNodes</param>

			</result>

		</action>

	</package>

</struts>

注意：

1.extends是json-default,表示返回json对象格式。

2.result中param的name为root,里面设置的值就是action中要返回的JSON对象

需要封装对象Tree

public class TreeNode {

	private static final long serialVersionUID = 1L;

	private String id;   // 节点id

	private String text; // 显示的节点文本

	private String state = "open"; // 节点状态,'open'或者'closed',默认是'open'

	private boolean checked;       // 指明检查节点是否选中.

	public TreeNode() {}

	public TreeNode(String id, String text, String state, boolean checked) {

		this.id = id;

		this.text = text;

		this.state = state;

		this.checked = checked;

	}

	//...省略setXX() getXX()

}

表结构如图
EasyUI实现异步加载tree(整合Struts2)

首先查询所有parentid为空值的数据,然后同时判断该节点下是否有子节点，如果有则状态是关闭状态

当继续展开树的时候会将该ID值传入,然后查询该节点的子节点。

action方法实现

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.ArrayList;

import java.util.List;

import com.home.util.ConnectionManager;

/**

 * 查询数据使用JDBC进行操作

 *

 */

public class TreeAction {

	private List<TreeNode> treeNodes = new ArrayList<TreeNode>(); //返回的JSON数据

	private String id; // 树组件使用的ID

	public String treeLoad() {

		Statement sta = null;

		ResultSet rs = null;

		try {

			Connection conn = ConnectionManager.getConnection();

			sta = conn.createStatement();

			String sql = "";

			if (id == null) {  //如果id为null则是根节点

				sql = "select * from easyui_tree where parentid = ''";

			} else {           //查询下面的子节点

				sql = "select * from easyui_tree where parentid = " + id;

			}

			rs = sta.executeQuery(sql);

			while (rs.next()) {

				String id = rs.getString("id");

				String name = rs.getString("name");

				TreeNode node = new TreeNode();

				node.setId(id);

				node.setText(name);

				node.setChecked(false);

				//判断是否有子节点，如果有则closed否则open

				if(isChildrenNode(id)){

					node.setState("closed");

				}else{

					node.setState("open");

				}

				treeNodes.add(node);

			}

			// 关闭所有资源

			ConnectionManager.closeAll(rs, sta, conn);

		} catch (SQLException e) {

			e.printStackTrace();

		}

		return "success";

	}

	/**

	 * 判断是否有子节点

	 *

	 * @return

	 */

	public boolean isChildrenNode(String id) {

		Boolean flag = false;

		Statement sta = null;

		ResultSet rs = null;

		try {

			Connection conn = ConnectionManager.getConnection();

			sta = conn.createStatement();

			String sql = "select * from easyui_tree where parentid = " + id;

			rs = sta.executeQuery(sql);

			while (rs.next()) {

				flag = true;

			}

			// 关闭所有资源

			ConnectionManager.closeAll(rs, sta, conn);

		} catch (SQLException e) {

			e.printStackTrace();

		}

		return flag;

	}

	public List<TreeNode> getTreeNodes() {

		return treeNodes;

	}

	public void setTreeNodes(List<TreeNode> treeNodes) {

		this.treeNodes = treeNodes;

	}

	public String getId() {

		return id;

	}

	public void setId(String id) {

		this.id = id;

	}

}

对获取Connection的方法进行了封装

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class ConnectionManager {

	public static final String DRIVER = "com.mysql.jdbc.Driver";

	public static final String URL = "jdbc:mysql://localhost:3306/easyui";

	public static final String USERNAME = "root";

	public static final String PASSWORD = "root";

	/**

	 * 通过静态代码块 注册数据库驱动

	 */

	static {

		try {

			Class.forName(DRIVER);

		} catch (ClassNotFoundException e) {

			e.printStackTrace();

		}

	}

	/**

	 * 获得Connection

	 *

	 * @return

	 */

	public static Connection getConnection() {

		Connection conn = null;

		try {

			conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);

		} catch (SQLException e) {

			e.printStackTrace();

		}

		return conn;

	}

	/**

	 * 关闭ResultSet

	 *

	 * @param rs

	 */

	public static void closeResultSet(ResultSet rs) {

		if (rs != null) {

			try {

				rs.close();

			} catch (SQLException e) {

				e.printStackTrace();

			}

		}

	}

	/**

	 * 关闭Statement

	 *

	 * @param st

	 */

	public static void closeStatement(Statement st) {

		if (st != null) {

			try {

				st.close();

			} catch (SQLException e) {

				e.printStackTrace();

			}

		}

	}

	/**

	 * 关闭Connection

	 *

	 * @param conn

	 */

	public static void closeConnection(Connection conn) {

		if (conn != null) {

			try {

				conn.close();

			} catch (SQLException e) {

				e.printStackTrace();

			}

		}

	}

	/**

	 * 关闭全部

	 *

	 * @param rs

	 * @param sta

	 * @param conn

	 */

	public static void closeAll(ResultSet rs, Statement sta, Connection conn) {

		closeResultSet(rs);

		closeStatement(sta);

		closeConnection(conn);

	}

}