Tài liệu J2EE TUTORIAL ppt

STEPHANIE BODOFF

J2EE TUTORIAL

Ebook.moet.gov.vn, 2008

J2EE Tutorial THE TM

J2EE Tutorial

Stephanie Bodoff

Dale Green

Kim Haase

Eric Jendrock

Monica Pawlan

Beth Stearns

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THE TM

Copyright © 2002 Sun Microsystems, Inc. 901 San Antonio Road, Palo Alto, CA 94303 USA.

All rights reserved.

Duke logo™ designed by Joe Palrang.

Sun, Sun Microsystems, Sun logo, Java, JDBC, JavaBeans, Enterprise JavaBeans, JavaServer Pages,

J2EE, J2SE, JavaMail, Java Naming and Directory Interface, EJB, and JSP are trademarks or registered

trademarks of Sun Microsystems, Inc. UNIX® is a registered trademark in the United States and other

countries, exclusively licensed through X/Open Company, Ltd. .

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Published simultaneously in Canada.

ISBN 0-201-79168-4

Text printed on recycled paper

1 2 3 4 5 6 7 8 9 10—MA—0605040302

First printing, March 2002

v

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxi

Chapter 1: Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Distributed Multitiered Applications 2

J2EE Components 3

J2EE Clients 4

Web Components 6

Business Components 6

Enterprise Information System Tier 8

J2EE Containers 8

Container Services 8

Container Types 9

Packaging 10

Development Roles 11

J2EE Product Provider 12

Tool Provider 12

Application Component Provider 12

Application Assembler 13

Application Deployer and Administrator 14

Reference Implementation Software 14

Database Access 15

J2EE APIs 15

Simplified Systems Integration 18

Tools 19

Contents

vi CONTENTS

Chapter 2: Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Setting Up 22

Getting the Example Code 22

Getting the Build Tool (ant) 22

Checking the Environment Variables 23

Starting the J2EE Server 23

Starting the deploytool 23

Creating the J2EE Application 24

Creating the Enterprise Bean 24

Coding the Enterprise Bean 24

Compiling the Source Files 26

Packaging the Enterprise Bean 26

Creating the J2EE Application Client 28

Coding the J2EE Application Client 28

Compiling the Application Client 31

Packaging the J2EE Application Client 31

Specifying the Application Client’s Enterprise Bean Reference 32

Creating the Web Client 32

Coding the Web Client 32

Compiling the Web Client 34

Packaging the Web Client 34

Specifying the Web Client’s Enterprise Bean Reference 35

Specifying the JNDI Names 35

Deploying the J2EE Application 37

Running the J2EE Application Client 37

Running the Web Client 38

Modifying the J2EE Application 39

Modifying a Class File 39

Adding a File 39

Modifying the Web Client 39

Modifying a Deployment Setting 40

Common Problems and Their Solutions 40

Cannot Start the J2EE Server 40

Compilation Errors 41

Deployment Errors 42

J2EE Application Client Runtime Errors 43

Web Client Runtime Errors 44

Detecting Problems With the Verifier Tool 45

Comparing Your EAR Files with Ours 45

When All Else Fails 45

CONTENTS vii

Chapter 3: Enterprise Beans . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

What Is an Enterprise Bean? 48

Benefits of Enterprise Beans 48

When to Use Enterprise Beans 49

Types of Enterprise Beans 49

What Is a Session Bean? 49

State Management Modes 50

When to Use Session Beans 51

What Is an Entity Bean? 51

What Makes Entity Beans Different from Session Beans? 52

Container-Managed Persistence 53

When to Use Entity Beans 56

What Is a Message-Driven Bean? 56

What Makes Message-Driven Beans Different from Session

and Entity Beans? 57

When to Use Message-Driven Beans 57

Defining Client Access with Interfaces 58

Remote Access 58

Local Access 59

Local Interfaces and Container-Managed Relationships 59

Deciding on Remote or Local Access 60

Performance and Access 61

Method Parameters and Access 61

The Contents of an Enterprise Bean 62

Naming Conventions for Enterprise Beans 62

The Life Cycles of Enterprise Beans 63

The Life Cycle of a Stateful Session Bean 63

The Life Cycle of a Stateless Session Bean 64

The Life Cycle of an Entity Bean 65

The Life Cycle of a Message-Driven Bean 67

Chapter 4: A Session Bean Example . . . . . . . . . . . . . . . . . . . . . 69

The CartEJB Example 70

Session Bean Class 70

Home Interface 74

Remote Interface 76

Helper Classes 76

Running the CartEJB Example 76

Other Enterprise Bean Features 78

Accessing Environment Entries 78

Comparing Enterprise Beans 80

Passing an Enterprise Bean’s Object Reference 80

viii CONTENTS

Chapter 5: Bean-Managed Persistence Examples. . . . . . . . . .83

The SavingsAccountEJB Example 84

Entity Bean Class 84

Home Interface 94

Remote Interface 96

Running the SavingsAccountEJB Example 97

deploytool Tips for Entity Beans with

Bean-Managed Persistence 99

Mapping Table Relationships for Bean-Managed Persistence 99

One-to-One Relationships 99

One-to-Many Relationships 103

Many-to-Many Relationships 110

Primary Keys for Bean-Managed Persistence 113

The Primary Key Class 113

Primary Keys in the Entity Bean Class 115

Getting the Primary Key 116

Handling Exceptions 116

Chapter 6: Container-Managed Persistence Examples . . . .119

Overview of the RosterApp Application 120

The PlayerEJB Code 121

Entity Bean Class 122

Local Home Interface 126

Local Interface 127

A Guided Tour of the RosterApp Settings 128

RosterApp 128

RosterClient 129

RosterJAR 130

TeamJAR 131

Method Invocations in RosterApp 136

Creating a Player 137

Adding a Player to a Team 138

Removing a Player 139

Dropping a Player from a Team 140

Getting the Players of a Team 141

Getting a Copy of a Team’s Players 142

Finding the Players by Position 144

Getting the Sports of a Player 145

Running the RosterApp Example 147

Setting Up 147

Deploying the Application 147

Running the Client 148

CONTENTS ix

deploytool Tips for Entity Beans with

Container-Managed Persistence 148

Specifying the Bean’s Type 148

Selecting the Persistent Fields and Abstract Schema Name 149

Defining EJB QL Queries for Finder and Select Methods 149

Generating SQL and Specifying Table Creation 149

Specifying the Database JNDI Name, User Name,

and Password 150

Defining Relationships 150

Primary Keys for Container-Managed Persistence 151

The Primary Key Class 151

Primary Keys in the Entity Bean Class 152

Generating Primary Key Values 153

Chapter 7: A Message-Driven Bean Example . . . . . . . . . . . . 155

Example Application Overview 156

The J2EE Application Client 157

The Message-Driven Bean Class 157

The onMessage Method 158

The ejbCreate and ejbRemove Methods 159

Running the SimpleMessageEJB Example 159

Starting the J2EE Server 159

Creating the Queue 159

Deploying the Application 159

Running the Client 160

deploytool Tips for Message-Driven Beans 160

Specifying the Bean’s Type and Transaction Management 161

Setting the Message-Driven Bean’s Characteristics 161

deploytool Tips for JMS Clients 162

Setting the Resource References 162

Setting the Resource Environment References 163

Specifying the JNDI Names 163

Chapter 8: Enterprise JavaBeans Query Language . . . . . . . 165

Terminology 166

Simplified Syntax 167

x CONTENTS

Example Queries 167

Simple Finder Queries 167

Finder Queries That Navigate to Related Beans 169

Finder Queries with Other Conditional Expressions 170

Select Queries 172

Full Syntax 173

BNF Symbols 173

BNF Grammar of EJB QL 173

FROM Clause 176

Path Expressions 179

WHERE Clause 182

SELECT Clause 190

EJB QL Restrictions 191

Chapter 9: Web Clients and Components. . . . . . . . . . . . . . . .193

Web Client Life Cycle 194

Web Application Archives 196

Creating a WAR File 197

Adding a WAR File to an EAR File 197

Adding a Web Component to a WAR File 198

Configuring Web Clients 199

Application-Level Configuration 199

WAR-Level Configuration 200

Component-Level Configuration 202

Deploying Web Clients 203

Running Web Clients 203

Updating Web Clients 204

Internationalizing Web Clients 206

Chapter 10: Java Servlet Technology . . . . . . . . . . . . . . . . . . . .209

What Is a Servlet? 210

The Example Servlets 211

Troubleshooting 215

Servlet Life Cycle 216

Handling Servlet Life-Cycle Events 216

Handling Errors 218

Sharing Information 218

Using Scope Objects 219

Controlling Concurrent Access to Shared Resources 220

Accessing Databases 221

Initializing a Servlet 222

CONTENTS xi

Writing Service Methods 222

Getting Information from Requests 223

Constructing Responses 225

Filtering Requests and Responses 227

Programming Filters 229

Programming Customized Requests and Responses 230

Specifying Filter Mappings 232

Invoking Other Web Resources 234

Including Other Resources in the Response 234

Transferring Control to Another Web Component 236

Accessing the Web Context 237

Maintaining Client State 238

Accessing a Session 238

Associating Attributes with a Session 238

Session Management 239

Session Tracking 240

Finalizing a Servlet 241

Tracking Service Requests 242

Notifying Methods to Shut Down 242

Creating Polite Long-Running Methods 243

Chapter 11: JavaServer Pages Technology . . . . . . . . . . . . . . . 245

What Is a JSP Page? 246

The Example JSP Pages 249

The Life Cycle of a JSP Page 253

Translation and Compilation 253

Execution 254

Initializing and Finalizing a JSP Page 256

Creating Static Content 257

Creating Dynamic Content 257

Using Objects within JSP Pages 257

JSP Scripting Elements 260

Including Content in a JSP Page 263

Transferring Control to Another Web Component 265

Param Element 265

Including an Applet 265

Extending the JSP Language 267

Chapter 12: JavaBeans Components in JSP Pages. . . . . . . . . 269

JavaBeans Component Design Conventions 270

Why Use a JavaBeans Component? 271

xii CONTENTS

Creating and Using a JavaBeans Component 272

Setting JavaBeans Component Properties 273

Retrieving JavaBeans Component Properties 275

Chapter 13: Custom Tags in JSP Pages . . . . . . . . . . . . . . . . . . .279

What Is a Custom Tag? 280

The Example JSP Pages 281

Using Tags 285

Declaring Tag Libraries 285

Types of Tags 286

Defining Tags 289

Tag Handlers 289

Tag Library Descriptors 290

Simple Tags 293

Tags with Attributes 294

Tags With Bodies 296

Tags That Define Scripting Variables 298

Cooperating Tags 302

Examples 304

An Iteration Tag 304

A Template Tag Library 308

How Is a Tag Handler Invoked? 313

Chapter 14: Transactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315

What Is a Transaction? 316

Container-Managed Transactions 316

Transaction Attributes 317

Rolling Back a Container-Managed Transaction 321

Synchronizing a Session Bean’s Instance Variables 322

Methods Not Allowed in Container-Managed Transactions 323

Bean-Managed Transactions 323

JDBC Transactions 324

JTA Transactions 325

Returning without Committing 326

Methods Not Allowed in Bean-Managed Transactions 327

Summary of Transaction Options for Enterprise Beans 327

Transaction Timeouts 328

Isolation Levels 328

Updating Multiple Databases 329

Transactions in Web Components 331

CONTENTS xiii

Chapter 15: Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333

Overview 334

Security Roles 335

Declaring and Linking Role References 335

Mapping Roles to J2EE Users and Groups 337

Web-Tier Security 337

Protecting Web Resources 337

Controlling Access to Web Resources 338

Authenticating Users of Web Resources 338

Using Programmatic Security in the Web Tier 340

Unprotected Web Resources 340

EJB-Tier Security 340

Declaring Method Permissions 341

Using Programmatic Security in the EJB Tier 341

Unprotected EJB-Tier Resources 342

Application Client-Tier Security 342

Specifying the Application Client’s Callback Handler 343

EIS-Tier Security 343

Configuring Sign-On 344

Container-Managed Sign-On 344

Component-Managed Sign-On 344

Configuring Resource Adapter Security 345

Propagating Security Identity 346

Configuring a Component’s Propagated Security Identity 346

Configuring Client Authentication 347

J2EE Users, Realms, and Groups 348

Managing J2EE Users and Groups 349

Setting Up a Server Certificate 350

Chapter 16: Resource Connections . . . . . . . . . . . . . . . . . . . . . 353

JNDI Names and Resource References 354

deploytool Tips for Resource References 354

Database Connections for Enterprise Beans 357

Coded Connections 357

Connection Pooling 359

Mail Session Connections 359

Running the ConfirmerEJB Example 361

URL Connections 362

Running the HTMLReaderEJB Example 363

xiv CONTENTS

Chapter 17: J2EE Connector Architecture. . . . . . . . . . . . . . . . .365

About Resource Adapters 366

Resource Adapter Contracts 366

Administering Resource Adapters 368

The Black Box Resource Adapters 369

Transaction Levels 369

Properties 370

Configuring JDBC Drivers 371

Resource Adapter Tutorial 372

Setting Up 372

Deploying the Resource Adapter 372

Testing the Resource Adapter 373

Common Client Interface 375

Overview of the CCI 375

Programming with the CCI 376

Writing a CCI Client 385

CCI Tutorial 386

Chapter 18: The Duke’s Bank Application. . . . . . . . . . . . . . . . .391

Enterprise Beans 393

Session Beans 394

Entity Beans 397

Helper Classes 397

Database Tables 398

Protecting the Enterprise Beans 400

Application Client 400

The Classes and Their Relationships 401

BankAdmin Class 403

EventHandle Class 404

DataModel Class 405

Web Client 408

Design Strategies 409

Web Client Life Cycle 410

Protecting the Web Resources 414

Internationalization 414