http断点续传简单实现（java)

/* ! FVD_8  
**SiteFileFetch.java vYybQ&E/  
*/ zr ~4@JTS  
package NetFox; J``5;%TJp  
import java.io.*; %H[~V f?d  
import java.net.*; rR4?*90vjj  

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public class SiteFileFetch extends Thread { ZcHd.1fXh  
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SiteInfoBean siteInfoBean = null; //文件信息Bean $0cE iq?Hf  
long[] nStartPos; //开始位置 gj7'43 ?W  
long[] nEndPos; //结束位置 vA{DF{S4  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 q>s`G  
long nFileLength; //文件长度 CHi t{ @9  
boolean bFirst = true; //是否第一次取文件 +y_V$q$G  
boolean bStop = false; //停止标志 A4*D3\>%u  
File tmpFile; //文件下载的临时信息 29nMm>P.e  
DataOutputStream output; //输出到文件的输出流 bZ#KfR  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Y>{%,d#s_  
public SiteFileFetch(SiteInfoBean bean) throws IOException Vp1Q^`a{G  
{ z%]3`_I  
siteInfoBean = bean; , {}S<^?]  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); sDvy(5  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); =Qn8Y`U  
if(tmpFile.exists ()) &k`/jl;u  
{ I-Q(kWc  
bFirst = false; Ld'3uM/  
read_nPos(); ;Za^).=  
} ?y@;=x!'  
else 5k c
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{ k!T-X2L=  
nStartPos = new long[bean.getNSplitter()]; 3t5WwrNh  
nEndPos = new long[bean.getNSplitter()]; p
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} @.=2*e.z|b  
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} c],Zw  
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public void run() u$ vLwJ|o  
{ -5\.\L3y)  
//获得文件长度 !MOcF5M  
//分割文件 PkOtg[Z  
//实例FileSplitterFetch ZC&~InN  
//启动FileSplitterFetch线程 9?|m ^  
//等待子线程返回 .4!wp&  
try{ :FixLr!q  
if(bFirst) 618bbftx{  
{ :io~{a#.2\  
nFileLength = getFileSize(); ^J@ Xsl  
if(nFileLength == -1) ;?gR,AKZ  
{ G[ q<P  
System.err.println("File Length is not known!"); yg%T{hyzH  
} (OG>=h8?  
else if(nFileLength == -2) CelM~W$=u  
{ $cGV)[KWp@  
System.err.println("File is not access!"); O_D;_v6Ii+  
} _z3^.QP  
else ^Uldyv/  
{ K&&YxX~3  
for(int i=0;i<nStartPos.length;i++) ?YM0VB,y  
{ g:>dF#  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); K14{c1  
} 
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for(int i=0;i<nEndPos.length-1;i++) ,f .#-  
{ <$%Y#I'zX  
nEndPos = nStartPos[i+1]; VKr oikz@]  
} &RlYw#*1.  
nEndPos[nEndPos.length-1] = nFileLength; 8yGo\\=T  
} aVn+@g<.  
} O.?q8T)n82  
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//启动子线程 A:?w1"7gT  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ^p~3H  
for(int i=0;i<nStartPos.length;i++) (!<G` ;}u  
{ =YR+`[bfI  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), EkP(]F  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), &^ =Y76  
nStartPos,nEndPos,i); P'k`H  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); M-5zsN  
fileSplitterFetch.start(); !?m8UE  
} =(,dI[v  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Rx4O?7;  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); L;'v,s  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", \fC}l Ll  
nEndPos = " + nFileLength); D]Gt=2\NG9  
// fileSplitterFetch[nPos.length-1].start(); MLn?t^v-  
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//等待子线程结束 d\rs/ee  
//int count = 0; Xx=.;FYk  
//是否结束while循环 GnW_^$Fs  
boolean breakWhile = false; 3q1u9`4;  
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while(!bStop) YwF\  
{ {qBbzBG  
write_nPos();  av!~B,  
Utility.sleep(500); wEIAU  
breakWhile = true; +|Qe/
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for(int i=0;i<nStartPos.length;i++) ^ `Y1  
{ 9Dx9alJR  
if(!fileSplitterFetch.bDownOver) q*{Dy1Tj  
{ ON$-g_s>)  
breakWhile = false; JOH=)+xj  
break; &M+fb4:_  
} e@L7p,  
} _qhYG1t  
if(breakWhile) CFx$r_!~  
break;  4K$d%  
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//count++; ESv&x6H  
//if(count>4) wz5*?[4  
// siteStop(); 6Vc&g  
} 8Vqh1<
 
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System.err.println("文件下载结束！"); 4O3-PU>N  
} gR) )K)  
catch(Exception e){e.printStackTrace ();} 54, (;  
} n>I NJ  

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//获得文件长度 :w 4Sba3  
public long getFileSize() +0WI;M4i  
{ s:#\U!>0`  
int nFileLength = -1; /CN`U7:E  
try{ OO+QH 2j  
URL url = new URL(siteInfoBean.getSSiteURL()); )}jXC4  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); G2}e@L0  
httpConnection.setRequestProperty("User-Agent","NetFox"); +eD+Z.{  
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int responseCode=httpConnection.getResponseCode(); ,_2ZKO/k$  
if(responseCode>=400) :*/`"M)'  
{ + %07J6  
processErrorCode(responseCode); ln6Hr^@5  
return -2; //-2 represent access is error -V)DKf"f  
} -:o4|&g<*  
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String sHeader; ];1Mg  
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for(int i=1;;i++) mdTCe HX  
{ NJraol  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); W{(q7>g  
//Utility.log(in.readLine()); ?ydqmj2[F  
sHeader=httpConnection.getHeaderFieldKey(i); m|w-}s,  
if(sHeader!=null) >HY( Ij<  
{ wR=WS',  
if(sHeader.equals("Content-Length")) 11(:#4Y,  
{ %^$7z,>;  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); /2e&fxxD  
break; lUd;u*A  
} 0xYPK7a=L\  
} jRP9e  
else |B;tv#mKD  
break; :v!e8kM\x  
} 9I;d>%  
} ]hL`HP  
catch(IOException e){e.printStackTrace ();} t$lO~~atr  
catch(Exception e){e.printStackTrace ();} zg2}R4h  
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Utility.log(nFileLength); sox0:9Oqnf  
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return nFileLength; 3b2[i,m<L  
} 58@YWvAk  
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//保存下载信息（文件指针位置） fGtUr_D  
private void write_nPos() j:;[Y`2  
{ :"9P {xe^  
try{ )E.!jL:g  
output = new DataOutputStream(new FileOutputStream(tmpFile)); rVE!mi]%  
output.writeInt(nStartPos.length); Pn*+g!`  
for(int i=0;i<nStartPos.length;i++) m["`Op4  
{ V_T.#"C4=z  
// output.writeLong(nPos); n@)Kf A)&  
output.writeLong(fileSplitterFetch.nStartPos); ~<?+(V^D  
output.writeLong(fileSplitterFetch.nEndPos); ,33[/j  
} L:ox$RU  
output.close(); N%k6*FBp~  
} M(alc9tn  
catch(IOException e){e.printStackTrace ();} YnzhvE  
catch(Exception e){e.printStackTrace ();} 1sqBBd"=PY  
} [%a
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//读取保存的下载信息（文件指针位置） .BR2pf|R  
private void read_nPos() Ip0~  
{ 8tR(i[L   
try{ <:mV^tK  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); %)$^_4.g  
int nCount = input.readInt(); :QGd/JX$n`  
nStartPos = new long[nCount]; 2|KgRk|!  
nEndPos = new long[nCount]; N<|_tC+ct  
for(int i=0;i<nStartPos.length;i++) [!ghI%VK  
{ wsnR$FhQ`  
nStartPos = input.readLong(); aeQvIob@  
nEndPos = input.readLong(); h2SVDKj  
} Y%FQ
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input.close(); 
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} ZPieL&uV`  
catch(IOException e){e.printStackTrace ();} zF9SZ#{a  
catch(Exception e){e.printStackTrace ();} 4'ym vR  
} L"|~,
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private void processErrorCode(int nErrorCode) kPm{tc  
{ ETw7/S${  
System.err.println("Error Code : " + nErrorCode); hGPo{>xR  
} J3F-Yl|  
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!\ IgTt,  
//停止文件下载 /A8ua=Kn  
public void siteStop() (aAv7kB&  
{ {{G`0i2KV  
bStop = true; Uq:WW1=kh  
for(int i=0;i<nStartPos.length;i++) G234UjN%  
fileSplitterFetch.splitterStop(); M7O5uW`  
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} ZPktZ  
} JumZ>\'p(  
//负责部分文件的抓取 </UUvMf"  
**FileSplitterFetch.java f4JmY1)@  
*/ ~6HpI0i  
package NetFox; :2'y=t#  
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import java.io.*; Nl[]8G};  
import java.net.*; *&f^R}O  
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public class FileSplitterFetch extends Thread { T
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String sURL; //File URL 9Q~9C9{+  
long nStartPos; //File Snippet Start Position Mbj{C  
long nEndPos; //File Snippet End Position q#{.8H-X'  
int nThreadID; //Thread's ID pO^PkX  
boolean bDownOver = false; //Downing is over Tz\PQ)!  
boolean bStop = false; //Stop identical DChqcdx~~  
FileAccessI fileAccessI = null; //File Access interface {XHAQ9'  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException y9K U&L2  
{ E[:eMJR  
this.sURL = sURL; zTgY=fuz  
this.nStartPos = nStart; $pKlF0 .  
this.nEndPos = nEnd; KASuSg+  
nThreadID = id; +-DF3(  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 skd3E4  
} Q[j'FtP%  
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public void run() (E{>L).~  
{ #%4XZ3j#j;  
while(nStartPos < nEndPos && !bStop) "!V-@F$@N  
{ R`[jkJrc  
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try{ z\d{A7  
URL url = new URL(sURL); ^tMb"WO  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); \dm5Em/  
httpConnection.setRequestProperty("User-Agent","NetFox"); prHM}n{0  
String sProperty = "bytes="+nStartPos+"-"; s+tPHftp  
httpConnection.setRequestProperty("RANGE",sProperty); .3X5
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Utility.log(sProperty); CIxa" MW  
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InputStream input = httpConnection.getInputStream(); #x?Ku\ts  
//logResponseHead(httpConnection);
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byte[] b = new byte[1024]; l}bAwJ?  
int nRead; SmpYH@  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Z<wJ!|f  
{ $U_M|Xa  
nStartPos += fileAccessI.write(b,0,nRead); GI se|[p  
//if(nThreadID == 1) AiP#wK;  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ]u]BxMs  
} t5| }0ID-  
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Utility.log("Thread " + nThreadID + " is over!"); Bj=lUn`T:  
bDownOver = true; = 9Ow!(!@  
//nPos = fileAccessI.write (b,0,nRead); x|b52<dLL&  
} i/C`]1R/  
catch(Exception e){e.printStackTrace ();} }508wwv  
} \aN*x  
} ':>u*  
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//打印回应的头信息 ]<3n;*8k?  
public void logResponseHead(HttpURLConnection con) !K8Kw W|X  
{ wD\viuq0  
for(int i=1;;i++) >1}@Q(n/}{  
{ o2 ;  
String header=con.getHeaderFieldKey(i); 9-W3}4'e  
if(header!=null) R_4eME2LB  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); O .ESI  
Utility.log(header+" : "+con.getHeaderField(header)); ;u8a%h!  
else S-f .NC}:i  
break; Ybkydc  
} *8bj3A]vf  
} VMee"'08  
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public void splitterStop() |JL?"cc  
{ ^ Fnag]qQ  
bStop = true; W ZT) LYA  
} YYN'LF#j  
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} kR+7JUq]  
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/* :R-_EY$k6  
**FileAccess.java Q}: $F{  
*//文件访问(定位，写) {>3J96  
package NetFox; :cxA  
import java.io.*; +n%d,Pz  
@DNwzdP  
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public class FileAccessI implements Serializable{ `53S[8  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 *x &  
RandomAccessFile oSavedFile; 'ln o#  
long nPos; z:ZXdB)L)  
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public FileAccessI() throws IOException Ygbyia|  
{ [[#R ry  
this("",0); B1V+CP3t  
} 3#0y.. F  
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public FileAccessI(String sName,long nPos) throws IOException LVNA`|>  
{ nWes,K6T  
oSavedFile = new RandomAccessFile(sName,"rw"); iYf)FPET  
this.nPos = nPos; 8og8;#mnyr  
oSavedFile.seek(nPos); q@^^jlHP  
} !,^y!+,Qy  
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public synchronized int write(byte[] b,int nStart,int nLen) ?Rk[P cX<  
{ uznYLS  
int n = -1; 8B(=Y;w  
try{ D$AvD7_  
oSavedFile.write(b,nStart,nLen); 1u8hnG  
n = nLen; +MqJJuWB  
} Hz"FGwd  
catch(IOException e) QHr'r/0  
{ !Ln 'Mi_B  
e.printStackTrace (); hD[r6c  
} AHo}K\O?r  
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return n; 9X&=?+f  
} kWacc&*|  
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} kTcW=AXu  
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/* T/.UMw  
**SiteInfoBean.java !rF
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*/ 0@um  
package NetFox; !9{hbmF#  
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public class SiteInfoBean { 2q(gWhcj  
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private String sSiteURL; //Site's URL D59q/@  
private String sFilePath; //Saved File's Path UpPl-jeT  
private String sFileName; //Saved File's Name ZWni5uF-c  
private int nSplitter; //Count of Splited Downloading File f62rm[  
l^^Z}3^Rk  
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public SiteInfoBean() zBK"k]rz  
{//nSplitter的缺省值为5 }Q*J!OH  
//default value of nSplitter is 5 )4h|7^6ji  
this("","","",5); !Eg2#a?  
} &8pGq./lr=  
!C|Z+w9Y  
{P,hH~!  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) %gQUog  
{ V'gJtF  
sSiteURL= sURL; lQiw8qD  
sFilePath = sPath; &Z3%UOY  
sFileName = sName; 8f1M
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this.nSplitter = nSpiltter; Bd 0oA )i  
5 1N/XEk  
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} omGzyuPF  
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public String getSSiteURL() 2 6DX4  
{ Hj(K*z  
return sSiteURL; ;5.<M<PH  
} ?PS?_+E\L  
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public void setSSiteURL(String value) (7N!Jvg9  
{ 71>,tq  
sSiteURL = value; 7_P33l8y  
} {8qcM8  
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public String getSFilePath() YXZP-=fB>i  
{ g4Q' Fub+I  
return sFilePath; P(FlU]q  
} pg!MtuC}  
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public void setSFilePath(String value) H2H[DVKv  
{ XI|k,Ko<  
sFilePath = value; d=meh4Y  
} %[5GGd5w  
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public String getSFileName() _3D9>8tzE7  
{ VKZP\]$XG  
return sFileName; m?4hEwQxf  
} NP\mzlI~@  
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public void setSFileName(String value) +lfO4^V  
{ mj
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sFileName = value; ~;]kqYIJ  
} |1tpXpe  
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^"
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public int getNSplitter() VBix8|  
{ I|c!:4  
return nSplitter; ]M
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} )XavhS~Ff  
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public void setNSplitter(int nCount) +or<(%o @  
{ OJ"./*H  
nSplitter = nCount; e ><0crb  
} 7l$ u.[  
} :N_]*>  
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Z'j[N4%B
K  
/* ~-6_-Y|  
**Utility.java Y%kOq`uT=n  
*/ vpf.0!zh  
package NetFox; f,E7eL@  
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[520!JhZY  
public class Utility { \eNB L[  
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public Utility() 1P[x.t#  
{ 8U(o@1PT  
[tof+0Y6  
h'};spv  
} B~ i  
]vB\yQE  
//线程睡眠 +a^gC  
public static void sleep(int nSecond) y]+5Y.Cw$  
{ k9OGnCW\  
try{ vm[*+&\2  
Thread.sleep(nSecond); 7@>/O)>(AS  
} ]b;m~|9  
catch(Exception e) xx>hJ!  
{ #"KC29!Yj  
e.printStackTrace (); !hZ: \&V  
} \Z3K ~  
} *!$Z5Im  
QEf@wv;T  
//日志 / @"{u0  
public static void log(String sMsg) pXl[I;  
{ 18sc|t  
System.err.println(sMsg); 5]LWWjT  
} QK+,63@D\=  
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public static void log(int sMsg) H}5
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{ vE'{?C=EM  
System.err.println(sMsg); M Zz21H  
} YIg43Av  
}
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9/29>K_  
/* PjEJC@n  
**TestMethod.java 1J"9Y81  
*/ g assOd  
package NetFox; b{ xlW }S  
s+lBai*#  
}' AY#g  
public class TestMethod { =n"kgn  
|EX=Rj*  
}q@#M8b  
public TestMethod() i,*m(C@F}  
{ ///xx/weblogic60b2_win.exe 9;U?_   
try{ t kj  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); N$]er'`  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); \\<=J[R.M  
SiteFileFetch fileFetch = new SiteFileFetch(bean); hA5')te<  
fileFetch.start(); A\Ib  
} H,L{N'[Xph  
catch(Exception e){e.printStackTrace ();} \(P?=] -  
E|f[#+:+  
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} U[f00m5{HV  
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public static void main(String[] args) 1Y'4 g3T  
{ ulIEx~qP  
new TestMethod(); 5F~l;zT  
} \6SjJ]o>  
} )Q =>7%ZA  
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