通过数据库数据构建树结构（一）

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设计主页

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连接数据库

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通过数据库表构建树结构

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添加详细信息页

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添加代码

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定义页面导航

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更多功能：将Action方法与树节点绑定

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关于树节点选择的注意事项

JavaServer Faces组件/
Java EE平台

1.2 with Java EE 5*
1.1 with J2EE 1.4

Travel数据库

必需

代码示例1：页面1的prerender方法

    public void prerender() {

        // If the Request Bean's personId is set, then

        // we just came back from the Trip page

        // and had displayed a selected trip.

        // We use the personId later to determine whether

        // to expand a person's node

        Integer expandedPersOnId= getRequestBean1().getPersonId();

        try {

            // Set up the variables we will need

            Integer currentPersOnId= new Integer(-1);

            // If nbrChildren is not 0 then this is a

            // postback and we have our tree already

            int nbrChildren = displayTree.getChildCount();

            if (nbrChildren == 0) {

                // List of outer (person) nodes

                List outerChildren = displayTree.getChildren();

                // Erase previous contents

                outerChildren.clear();

                // List of inner (trip) nodes

                List innerChildren = null;

                // Execute the SQL query

                tripDataProvider.refresh();

                // Iterate over the rows of the result set.

                // Every time we encounter a new person, add first level node.

                // Add second level trip nodes to the parent person node.

                boolean hasNext = tripDataProvider.cursorFirst();

                while (hasNext) {

                    Integer newPersOnId=

                            (Integer) tripDataProvider.getValue(

                            "TRIP.PERSONID");

                    if (!newPersonId.equals(currentPersonId)) {

                        currentPersOnId= newPersonId;

                        TreeNode persOnNode= new TreeNode();

                        personNode.setId("person" + newPersonId.toString());

                        personNode.setText(

                                (String)tripDataProvider.getValue(

                                "PERSON.NAME"));

                        // If the request bean passed a person id,

                        // expand that person's node

                        personNode.setExpanded(newPersonId.equals

                                (expandedPersonId));

                        outerChildren.add(personNode);

                        innerChildren = personNode.getChildren();

                    }

                    // Create a new trip node

                    TreeNode tripNode = new TreeNode();

                    tripNode.setId("trip" +

                            tripDataProvider.getValue("TRIP.TRIPID").toString());

                    tripNode.setText(

                            tripDataProvider.getValue("TRIP.DEPDATE").toString());

                    tripNode.setUrl("/faces/Trip.jsp?tripId=" +

                            tripDataProvider.getValue("TRIP.TRIPID").toString());

                    innerChildren.add(tripNode);

                    hasNext = tripDataProvider.cursorNext();

                }

            }

        } catch (Exception ex) {

            log("Exception gathering tree data", ex);

            error("Exception gathering tree data: " + ex);

        } 

     }