javaweb使用Thymeleaf 最凝练的CRUD项目-下

10、执行保存

①目标

提交表单后，将表单数据封装为Soldier对象，然后将Soldier对象保存到数据库。

②思路

③代码

[1]Servlet方法

protected void saveSoldier(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

// 1.获取请求参数
String soldierName = request.getParameter("soldierName");
String soldierWeapon = request.getParameter("soldierWeapon");

// 2.创建Soldier对象
Soldier soldier = new Soldier(null, soldierName, soldierWeapon);

// 3.调用Service方法
soldierService.saveSoldier(soldier);

// 4.重定向请求
response.sendRedirect(request.getContextPath() + "/SoldierServlet?method=showList");

}

[2]Service方法

@Override
public void saveSoldier(Soldier soldier) {

    soldierDao.insertSoldier(soldier);

}

[3]Dao方法

@Override
public void insertSoldier(Soldier soldier) {

    String sql = "insert into t_soldier(soldier_name,soldier_weapon) values(?,?)";

    update(sql, soldier.getSoldierName(), soldier.getSoldierWeapon());
}

11、前往修改信息的表单页面

①创建超链接

<a th:href="@{/SoldierServlet(soldierId=${soldier.soldierId},method=toEditPage)}"></a>

②Servlet方法

执行步骤

1. 从请求参数获取soldierId
2. 根据soldierId查询Soldier对象
3. 将Soldier对象存入请求域
4. 前往更新的表单页面

protected void toEditPage(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

// 1.从请求参数获取soldierId
String soldierId = request.getParameter("soldierId");

// 2.根据soldierId查询Soldier对象
Soldier soldier = soldierService.getSoldierById(soldierId);

// 3.将Soldier对象存入请求域
request.setAttribute("soldier", soldier);

// 4.前往更新的表单页面
processTemplate("edit-page", request, response);

}

③Service方法

@Override
public Soldier getSoldierById(String soldierId) {
    return soldierDao.selectSoldierByPrimaryKey(soldierId);
}

④Dao方法

@Override
public Soldier selectSoldierByPrimaryKey(String soldierId) {
    String sql = "select soldier_id soldierId,soldier_name soldierName,soldier_weapon soldierWeapon from t_soldier where soldier_id=?";

    return getBean(Soldier.class, sql, soldierId);
}

⑤表单页面

<form th:action="@{/SoldierServlet}" method="post">

    <input type="hidden" name="method" value="updateSoldier" />
    <input type="hidden" name="soldierId" th:value="${soldier.soldierId}" />

    士兵姓名：<input type="text" name="soldierName" th:value="${soldier.soldierName}" /><br/>
    士兵武器：<input type="text" name="soldierWeapon" th:value="${soldier.soldierWeapon}" /><br/>

    <button type="submit">更新</button>

</form>

12、执行更新

①Servlet方法

执行步骤

1.获取请求参数
2.封装对象
3.调用Service方法执行更新
4.重定向请求

protected void updateSoldier(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    // 1.获取请求参数
    String soldierIdOrigin = request.getParameter("soldierId");
    Integer soldierId = Integer.parseInt(soldierIdOrigin);
    String soldierName = request.getParameter("soldierName");
    String soldierWeapon = request.getParameter("soldierWeapon");

    // 2.封装对象
    Soldier soldier = new Soldier(soldierId, soldierName, soldierWeapon);

    // 3.调用Service方法执行更新
    soldierService.updateSoldier(soldier);

    // 4.重定向请求
    response.sendRedirect(request.getContextPath() + "/SoldierServlet?method=showList");
}

②Service方法

@Override
public void updateSoldier(Soldier soldier) {

    soldierDao.updateSoldier(soldier);

}

③Dao方法

@Override
public void updateSoldier(Soldier soldier) {
    String sql = "update t_soldier set soldier_name=?,soldier_weapon=? where soldier_id=?";
    update(sql, soldier.getSoldierName(), soldier.getSoldierWeapon(), soldier.getSoldierId());
}

13、请求字符集设置

• 设置请求体字符集需要调用request.setCharacterEncoding(“UTF-8”);
• request.setCharacterEncoding(“UTF-8”);要求在所有request.getParameter()前面
• 在执行子类Servlet方法时，其实都是先调用父类ModelBaseServlet的doPost()方法
• doPost()方法中包含获取method请求参数的操作
• 所以最前面的request.getParameter()在doPost()方法中
• 所以request.setCharacterEncoding(“UTF-8”);要放在doPost()方法的request.getParameter()前面

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

// 0.在所有request.getParameter()前面设置解析请求体的字符集
request.setCharacterEncoding("UTF-8");

// 1.从请求参数中获取method对应的数据
String method = request.getParameter("method");

// ……