[ch04] 4.9, Implemented Filter.

Signed-off-by: Dongho Sim <dhsim86@gmail.com>

src/main/java/Lesson04/CharacterEncodingFilter.java

@@ -0,0 +1,31 @@
+package Lesson04;
+
+import javax.servlet.*;
+import java.io.IOException;
+
+/**
+ * Created by Dongho on 2017. 3. 8..
+ */
+public class CharacterEncodingFilter implements Filter {
+
+    FilterConfig filterConfig;
+
+    @Override
+    public void init(FilterConfig filterConfig) throws ServletException {
+        this.filterConfig = filterConfig;
+    }
+
+    @Override
+    public void doFilter(
+        ServletRequest request, ServletResponse response, FilterChain nextFilter)
+        throws IOException, ServletException {
+
+        request.setCharacterEncoding(filterConfig.getInitParameter("encoding"));
+        nextFilter.doFilter(request, response);
+    }
+
+    @Override
+    public void destroy() {
+
+    }
+}

src/main/java/Lesson04/MemberAddServlet.java

@@ -48,8 +48,6 @@ protected void doPost(HttpServletRequest request, HttpServletResponse response)
         try {
             ServletContext sc = this.getServletContext();
 
-            request.setCharacterEncoding("UTF-8");
-
             Class.forName(sc.getInitParameter("driver"));
             conn = DriverManager.getConnection(
                 sc.getInitParameter("url"),

src/main/java/Lesson04/MemberDeleteServlet.java

@@ -10,7 +10,6 @@
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.PreparedStatement;
-import java.sql.Statement;
 
 /**
  * Created by Dongho on 2017. 3. 7..
@@ -43,7 +42,6 @@ protected void doGet(HttpServletRequest request, HttpServletResponse response)
             stmt.setInt(1, Integer.parseInt(request.getParameter("no")));
 
             stmt.executeUpdate();
-
             response.sendRedirect("list");
         }
         catch (Exception e) {

src/main/java/Lesson04/MemberUpdateServlet.java

@@ -78,8 +78,6 @@ protected void doPost(
         HttpServletRequest request, HttpServletResponse response
     ) throws ServletException, IOException {
 
-        request.setCharacterEncoding("UTF-8");
-
         Connection conn = null;
         PreparedStatement stmt = null;
 

src/main/webapp/WEB-INF/web.xml

@@ -23,6 +23,23 @@
         <param-value>study</param-value>
     </context-param>
 
+    <!-- filters -->
+    <filter>
+        <filter-name>CharacterEncodingFilter</filter-name>
+        <filter-class>Lesson04.CharacterEncodingFilter</filter-class>
+
+        <init-param>
+            <param-name>encoding</param-name>
+            <param-value>UTF-8</param-value>
+        </init-param>
+    </filter>
+
+    <!-- filter mapping -->
+    <filter-mapping>
+        <filter-name>CharacterEncodingFilter</filter-name>
+        <url-pattern>/*</url-pattern>
+    </filter-mapping>
+
     <!-- servlets -->
     <servlet>
       <servlet-name>Hello</servlet-name>