そもそも、Proxyクラスとは?
メソッドの実行前後に何か処理させたいって時に使うものっすね。
例えば、こんなの↓を実装できたりします。
java.sql.Connectionプロキシの素 - Qiita
しかし、インターフェイスによってはメソッド数が多すぎて
一つ一つ手で作っていったら何か間違いが起きそうで🍣、
IDEで自動生成しちゃいましょう。
余談
プロキシは↓のように他にも方法が色々あるので、まずはどれがいいか検討してみよう。
- java.lang.reflect.Proxyでプログラムチックにプロキシ作るのも手
- SpringなどのFWを使ってAOPして、FWのやり方にはめるのも手
さあ、IntelliJ IDEAの機能で早速作ってみるぞ
HttpServletRequest
というインターフェイスを例にやってみます。
1. まずは以下のようなプロキシの元となるコードを書きましょう。
インターフェイスをimplementsしたクラスを作ってください。
そして、プロキシの元となるフィールドとコンストラクタ―を書いてください。
import javax.servlet.http.HttpServletRequest;
public class HttpServletRequestProxy2 implements HttpServletRequest {
private HttpServletRequest delegate;
public HttpServletRequestProxy2(HttpServletRequest delegate){
this.delegate = delegate;
}
}
2. クラス名にカーソルを置いた状態でAlt + Insertを押してDelegate Methods...
を押す
3.さっきのプロキシの元とするフィールドを1個選択する
4. 生成するメソッドを選択する(基本的にはAlt + Aで全選択してOK)
完成
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.Principal;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Map;
public class HttpServletRequestProxy implements HttpServletRequest {
private HttpServletRequest delegate;
public HttpServletRequestProxy(HttpServletRequest delegate){
this.delegate = delegate;
}
@Override
public String getAuthType() {
return delegate.getAuthType();
}
@Override
public Cookie[] getCookies() {
return delegate.getCookies();
}
@Override
public long getDateHeader(String name) {
return delegate.getDateHeader(name);
}
@Override
public String getHeader(String name) {
return delegate.getHeader(name);
}
@Override
public Enumeration<String> getHeaders(String name) {
return delegate.getHeaders(name);
}
@Override
public Enumeration<String> getHeaderNames() {
return delegate.getHeaderNames();
}
@Override
public int getIntHeader(String name) {
return delegate.getIntHeader(name);
}
@Override
public String getMethod() {
return delegate.getMethod();
}
@Override
public String getPathInfo() {
return delegate.getPathInfo();
}
@Override
public String getPathTranslated() {
return delegate.getPathTranslated();
}
@Override
public String getContextPath() {
return delegate.getContextPath();
}
@Override
public String getQueryString() {
return delegate.getQueryString();
}
@Override
public String getRemoteUser() {
return delegate.getRemoteUser();
}
@Override
public boolean isUserInRole(String role) {
return delegate.isUserInRole(role);
}
@Override
public Principal getUserPrincipal() {
return delegate.getUserPrincipal();
}
@Override
public String getRequestedSessionId() {
return delegate.getRequestedSessionId();
}
@Override
public String getRequestURI() {
return delegate.getRequestURI();
}
@Override
public StringBuffer getRequestURL() {
return delegate.getRequestURL();
}
@Override
public String getServletPath() {
return delegate.getServletPath();
}
@Override
public HttpSession getSession(boolean create) {
return delegate.getSession(create);
}
@Override
public HttpSession getSession() {
return delegate.getSession();
}
@Override
public boolean isRequestedSessionIdValid() {
return delegate.isRequestedSessionIdValid();
}
@Override
public boolean isRequestedSessionIdFromCookie() {
return delegate.isRequestedSessionIdFromCookie();
}
@Override
public boolean isRequestedSessionIdFromURL() {
return delegate.isRequestedSessionIdFromURL();
}
@Override
public boolean isRequestedSessionIdFromUrl() {
return delegate.isRequestedSessionIdFromUrl();
}
@Override
public boolean authenticate(HttpServletResponse response) throws IOException, ServletException {
return delegate.authenticate(response);
}
@Override
public void login(String username, String password) throws ServletException {
delegate.login(username, password);
}
@Override
public void logout() throws ServletException {
delegate.logout();
}
@Override
public Collection<Part> getParts() throws IOException, ServletException {
return delegate.getParts();
}
@Override
public Part getPart(String name) throws IOException, ServletException {
return delegate.getPart(name);
}
@Override
public Object getAttribute(String name) {
return delegate.getAttribute(name);
}
@Override
public Enumeration<String> getAttributeNames() {
return delegate.getAttributeNames();
}
@Override
public String getCharacterEncoding() {
return delegate.getCharacterEncoding();
}
@Override
public void setCharacterEncoding(String env) throws UnsupportedEncodingException {
delegate.setCharacterEncoding(env);
}
@Override
public int getContentLength() {
return delegate.getContentLength();
}
@Override
public String getContentType() {
return delegate.getContentType();
}
@Override
public ServletInputStream getInputStream() throws IOException {
return delegate.getInputStream();
}
@Override
public String getParameter(String name) {
return delegate.getParameter(name);
}
@Override
public Enumeration<String> getParameterNames() {
return delegate.getParameterNames();
}
@Override
public String[] getParameterValues(String name) {
return delegate.getParameterValues(name);
}
@Override
public Map<String, String[]> getParameterMap() {
return delegate.getParameterMap();
}
@Override
public String getProtocol() {
return delegate.getProtocol();
}
@Override
public String getScheme() {
return delegate.getScheme();
}
@Override
public String getServerName() {
return delegate.getServerName();
}
@Override
public int getServerPort() {
return delegate.getServerPort();
}
@Override
public BufferedReader getReader() throws IOException {
return delegate.getReader();
}
@Override
public String getRemoteAddr() {
return delegate.getRemoteAddr();
}
@Override
public String getRemoteHost() {
return delegate.getRemoteHost();
}
@Override
public void setAttribute(String name, Object o) {
delegate.setAttribute(name, o);
}
@Override
public void removeAttribute(String name) {
delegate.removeAttribute(name);
}
@Override
public Locale getLocale() {
return delegate.getLocale();
}
@Override
public Enumeration<Locale> getLocales() {
return delegate.getLocales();
}
@Override
public boolean isSecure() {
return delegate.isSecure();
}
@Override
public RequestDispatcher getRequestDispatcher(String path) {
return delegate.getRequestDispatcher(path);
}
@Override
public String getRealPath(String path) {
return delegate.getRealPath(path);
}
@Override
public int getRemotePort() {
return delegate.getRemotePort();
}
@Override
public String getLocalName() {
return delegate.getLocalName();
}
@Override
public String getLocalAddr() {
return delegate.getLocalAddr();
}
@Override
public int getLocalPort() {
return delegate.getLocalPort();
}
@Override
public ServletContext getServletContext() {
return delegate.getServletContext();
}
@Override
public AsyncContext startAsync() throws IllegalStateException {
return delegate.startAsync();
}
@Override
public AsyncContext startAsync(ServletRequest servletRequest, ServletResponse servletResponse) throws IllegalStateException {
return delegate.startAsync(servletRequest, servletResponse);
}
@Override
public boolean isAsyncStarted() {
return delegate.isAsyncStarted();
}
@Override
public boolean isAsyncSupported() {
return delegate.isAsyncSupported();
}
@Override
public AsyncContext getAsyncContext() {
return delegate.getAsyncContext();
}
@Override
public DispatcherType getDispatcherType() {
return delegate.getDispatcherType();
}
}