albert's blog: October 2018

2018/10/31

[Travel] 201810 桃園

大溪中正公園

木藝生態博物館壹號館

武德殿

2018/10/15

[Neo4j] How to implement having clause in cypher?

假設我透過以下 Cypher 語法，查詢到在某時間區間內，每個醫生、開立某種藥物以及次數

match (doc:Doctor)-[r1:PRESCRIBES]->(med:Medicine)
where r1.date >= "20180401" and r1.date <= "20180415"     
with doc.name as doctor, med.name as medicine, count(med.name) as prescription_frequency
return doctor, medicine, prescription_frequency
order by prescription_frequency desc

如果我想要撈出 prescription_frequency >= 3 的資料，語法修正如下：

match (doc:Doctor)-[r1:PRESCRIBES]->(med:Medicine)
where r1.date >= "20180401" and r1.date <= "20180415"     
with doc.name as doctor, med.name as medicine, count(med.name) as prescription_frequency 
where prescription_frequency >= 3
return doctor, medicine, prescription_frequency
order by prescription_frequency desc

2018/10/14

[Spring Boot] How to create a simple restful service

Scenario

How-To
Rest Controller:

package springboot.rest.controller;

import java.util.ArrayList;
import java.util.List;

import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import springboot.rest.vo.Book;

@RestController
@RequestMapping("/api/books")
public class BookController {

    private static List<Book> books = new ArrayList<Book>();

    static {
        Book book1 = new Book("1501108085", "Peaks and Valleys", "Spencer Johnson M.D.");
        Book book2 = new Book("0062102419", "How Will You Measure Your Life?", "Clayton M. Christensen");
        Book book3 = new Book("111908833X", "Bogle On Mutual Funds", "John C. Bogle");

        books.add(book1);
        books.add(book2);
        books.add(book3);
    }

    @GetMapping
    public String getBooks() throws JsonProcessingException {
        String booksJSON = "";
        try {
            ObjectMapper objectMapper = new ObjectMapper();
            booksJSON = objectMapper.writeValueAsString(books);
        } catch (JsonProcessingException e) {
            throw e;
        }
        return booksJSON;
    }

    @PostMapping(value = "/add")
    public String addBook(@RequestBody Book book) throws JsonProcessingException {
        books.add(book);

        String booksJSON = "";
        try {
            ObjectMapper objectMapper = new ObjectMapper();
            booksJSON = objectMapper.writeValueAsString(books);
        } catch (JsonProcessingException e) {
            throw e;
        }
        return booksJSON;
    }

    @PutMapping(value = "/update")
    public String updateBook(@RequestBody Book book) throws JsonProcessingException {
        books.stream().forEach(b -> {
            if (b.getName().equals(book.getName())) {
                b.setIsbn(book.getIsbn());
            }
        });
        String booksJSON = "";
        try {
            ObjectMapper objectMapper = new ObjectMapper();
            booksJSON = objectMapper.writeValueAsString(books);
        } catch (JsonProcessingException e) {
            throw e;
        }
        return booksJSON;
    }

    @DeleteMapping(value = "/delete/{isbn}")
    public String deleteBook(@PathVariable String isbn) throws JsonProcessingException {
        books.removeIf(b -> b.getIsbn().equals(isbn));
        String booksJSON = "";
        try {
            ObjectMapper objectMapper = new ObjectMapper();
            booksJSON = objectMapper.writeValueAsString(books);
        } catch (JsonProcessingException e) {
            throw e;
        }
        return booksJSON;
    }
}

Value object:

package springboot.rest.vo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
public class Book {

    private String isbn;
    private String name;
    private String author;
    
}

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>springboot</groupId>
    <artifactId>rest</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>rest</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <java.version>1.8</java.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <jackson.version>2.9.5</jackson.version>
        <springboot.version>2.0.0.RELEASE</springboot.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>${springboot.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <version>${springboot.version}</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.18</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>${jackson.version}</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>${jackson.version}</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

[Test Result] Get all books

[Test Result] Add a new book

[Test Result] Update a book

[Test Result] Delete book by ISBN

2018/10/13

[Java] How to write a client program to call restful service

Scenario

How-To
Client code:

package test.albert.rest.client;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Date;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.StringRequestEntity;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class RestClient {

    private final String GET_URL = "http://localhost:8080/api/greeting/get/sayHi?name=Albert";
    private final String POST_URL = "http://localhost:8080/api/greeting/post/sayHi";

    public static void main(String[] args) throws IOException {
        RestClient client = new RestClient();
        client.doGetRequest();
        client.doPostRequest();
    }

    public void doGetRequest() throws IOException {
        HttpClient client = new HttpClient();
        GetMethod getMethod = new GetMethod(GET_URL);
        try {
            int statusCode = client.executeMethod(getMethod);
            if (statusCode != HttpStatus.SC_OK) {
                String error = "do Get Request failed: " + getMethod.getStatusLine();
                throw new RuntimeException(error);
            }

            String responseBodyStr = getMethod.getResponseBodyAsString();
            log.debug("[doGetRequest] responseBodyStr = " + responseBodyStr);
        } catch (IOException e) {
            throw e;
        } finally {
            getMethod.releaseConnection();
        }
    }

    public void doPostRequest() throws JsonProcessingException, UnsupportedEncodingException {
        String greetingJson = createJSON();
        StringRequestEntity requestEntity = new StringRequestEntity(greetingJson, "application/json", "UTF-8");

        HttpClient client = new HttpClient();

        PostMethod postMethod = new PostMethod(POST_URL);
        postMethod.setRequestEntity(requestEntity);

        try {
            int statusCode = client.executeMethod(postMethod);
            if (statusCode != HttpStatus.SC_OK) {
                String error = "do Post Request failed: " + postMethod.getStatusLine();
                throw new RuntimeException(error);
            }
            
            String responseStr = postMethod.getResponseBodyAsString();
            log.debug("[doPostRequest] responseStr = " + responseStr);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            postMethod.releaseConnection();
        }

    }

    private String createJSON() throws JsonProcessingException {
        Greeting greeting = new Greeting("Hello, Mandy", null);
        return new ObjectMapper().writeValueAsString(greeting);
    }

    @AllArgsConstructor
    @NoArgsConstructor
    @Data
    @ToString
    private static class Greeting {
        private String content;

        @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm:ss.SSS", timezone = "GMT+8")
        private Date datetime;
    }

}

Add dependency into pom.xml

        <dependency>
            <groupId>commons-httpclient</groupId>
            <artifactId>commons-httpclient</artifactId>
            <version>3.1</version>
        </dependency>
  
 <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.9.3</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.3</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.9.3</version>
        </dependency>

2018/10/12

[Spring Boot] How to create a simple restful service

Scenario

How-To
Restful Controller:

package springboot.rest.controller;

import java.util.Date;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import springboot.rest.vo.Greeting;

@RestController
@RequestMapping("/api/greeting")
public class GreetingController {

    @GetMapping("/get/sayHi")
    public String greeting(@RequestParam(value = "name") String name) throws JsonProcessingException {
        Greeting greeting = new Greeting("Hello, " + name, new Date());
        String greetingJson = "";
        try {
            ObjectMapper objectMapper = new ObjectMapper();
            greetingJson = objectMapper.writeValueAsString(greeting);
        } catch (JsonProcessingException e) {
            throw e;
        }
        return greetingJson;
    }

    @PostMapping(value = "/post/sayHi")
    public String greeting(@RequestBody Greeting greeting) throws JsonProcessingException {
        Greeting greetingVo = new Greeting(greeting.getContent(), new Date());
        String greetingJson = "";
        try {
            ObjectMapper objectMapper = new ObjectMapper();
            greetingJson = objectMapper.writeValueAsString(greetingVo);
        } catch (JsonProcessingException e) {
            throw e;
        }
        return greetingJson;
    }

}

Value Object:

package springboot.rest.vo;

import java.util.Date;

import com.fasterxml.jackson.annotation.JsonFormat;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

@AllArgsConstructor
@NoArgsConstructor
@Data
@ToString
public class Greeting {

    private String content;

    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm:ss.SSS", timezone = "GMT+8")
    private Date datetime;
}

Make the application executable:

package springboot.rest;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class App {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>springboot</groupId>
    <artifactId>rest</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>rest</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <java.version>1.8</java.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <jackson.version>2.9.5</jackson.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.0.0.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.18</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>${jackson.version}</version>
        </dependency>
        
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>${jackson.version}</version>
        </dependency>
    </dependencies>
</project>

Test Result:

Total Pageviews

2018/10/31

[Travel] 201810 桃園

2018/10/15

[Neo4j] How to implement having clause in cypher?

2018/10/14

[Spring Boot] How to create a simple restful service

2018/10/13

[Java] How to write a client program to call restful service

2018/10/12

[Spring Boot] How to create a simple restful service